Biomedical subjects

T Murakami

Publications and source records attributed to T Murakami.

At least 19 recordsLinked to original sources

PubMed1992

Reversible interactions between plasminogen activators and plasminogen activator inhibitor-1.

We have shown that the urokinase (UK) kringle domain contains a high-affinity plasminogen activator inhibitor-1 (PAI-1) binding site, responsible for the 10-fold faster complex formation between UK and PAI-1 than between PAI-1 and low-molecular-weight urokinase (LMWUK). Complex formation between UK and PAI-1, but not between LMWUK and PAI-1, was suppressed 10-fold in the presence of peptide U-107 derived from the UK kringle domain. Peptide U-373 derived from the UK catalytic domain slowed complex formation between UK and PAI-1 and also LMWUK and PAI-1. Inactivation of tissue-type plasminogen activator (tPA) by PAI-1 was slowed 10-fold in the presence of peptides derived from the tPA finger and kringle-2 domains. DFP-inactivated (DIP) UK and both forms of DIP-tPA inhibited PAI-1 binding to U-107 and to U-373 whereas single-chain urokinase-type PA (scuPA) was unable to compete with either peptide for PAI-1 binding. These data suggest that the reversible PAI-1 binding site in the UK A-chain plays a role in the rapid association with PAI-1 as important as those that reside in the tPA A-chain and that reversible PAI-1 binding sites are expressed on the surface of UK upon conversion from scuPA, in contrast to tPA.

Amino Acid Sequence↗

PubMed1992

[MR imaging evaluation of plica synoviallis mediopatellaris of the knee joint].

To evaluate the diagnostic ability of MR imaging for plica synoviallis mediopatellaris (PSM), we retrospectively reviewed the MR imaging findings of patellofemoral space in 20 knee joints of 11 patients. In all 20 knee joints, arthroscopy and MR imaging were available. MR imaging was performed with a 1.5 Tesla Magnetom (Siemens) using a round surface coil. Pulse sequences were SE (TR 600 ms/TE 26 ms), SE (TR 200 ms/TE 26, 70 ms) and FLASH (TR 450 ms/TE 15 ms/FA 90 degrees). In six of the 20 knees with PSM proved by arthroscopy, a low intensity band was shown above the medial condyle of the femur on both T1- and T2-weighted MR images, and on FLASH images this band was shown as intermediate intensity. In the other 14 knees with no PSM observed by arthroscopy, the low intensity band was not shown on MR imaging. In all 20 knees, a similar low intensity band was shown about 1 cm cranial to the medial condyle of the femur. This should not be diagnosed as PSM. The low intensity band seen on T1- and T2-weighted MR images and its anatomical relation to the medial condyle are important in diagnosing PSM.

Adolescent↗

PubMed1992

[Experimental study of indirect lymphography with iodinated starch].

Opacification of lymph nodes on CT was attempted by means of indirect lymphography with iodinated starch (IS). Sixty percent solutions of two different molecular weights of IS were prepared (5,000 mol wt and 70,000 mol wt in average). After subcutaneous injection of IS solutions to the pedal area of dogs, CT scans were performed to evaluate opacification of the popliteal lymph nodes. The lymph nodes began to be opacified from 10 min after the injection of each solution. The high molecular weight IS showed higher attenuation and longer duration of opacification than did the low molecular weight IS. Homogeneity of opacification was better with latter. The optimum molecular weight for this purpose is considered to be between 5,000 and 70,000 mol wt.

Animals↗

PubMed1992

A novel anti-HIV synthetic peptide, T-22 ([Tyr5,12,Lys7]-polyphemusin II).

Tachyplesin and polyphemusin are antimicrobial peptides recently isolated from the hemocytes of horseshoe crabs (Tachypleus tridentatus and Limulus polyphemus). We synthesized them and their analogs and examined their antiviral activity against human immunodeficiency virus (HIV) type 1 in vitro. The infection of human T cells with the virus was markedly inhibited by some of them at low concentrations. In this structure-activity study, we found that [Tyr5,12, Lys7]-polyphemusin II, which was designated as T22, had extremely high anti-HIV activity. Its 50% inhibitory concentration (EC50) was 0.008 micrograms/ml, while its 50% cytotoxic concentration (CC50) was 54 micrograms/ml and these values were comparable to those of AZT. This result indicates that T22 would be a potential candidate for the therapy of HIV infection.

Amino Acid Sequence↗

PubMed1992

Convergence of excitatory inputs from the chorda tympani, glossopharyngeal, and vagus nerves onto inferior salivatory nucleus neurons in the cat.

Inferior salivatory nucleus (ISN) neurons were identified by their antidromic spike responses to tympanic nerve stimulation, and their responses to stimulation of the ipsilateral chorda tympani, glossopharyngeal, and vagus nerves were investigated in urethane-chloralose-anesthetized cats. Of the 53 ISN neurons identified, stimulation of at least one of these nerves evoked spike responses in 35 (66%), and 25 (47%) were excited by inputs from more than two stimulated nerves. The mean latencies of the reflex responses evoked by stimulation of the chorda tympani, glossopharyngeal, and vagus nerves were 10.4, 13.7, and 18.9 ms, respectively.

Action Potentials↗

PubMed1992

A novel transthyretin mutation at position 30 (Leu for Val) associated with familial amyloidotic polyneuropathy.

A novel transthyretin (TTR) mutation associated with familial amyloidotic polyneuropathy was detected in a Japanese patient. Single-strand conformation polymorphism analysis and sequence analysis of polymerase chain reaction (PCR)-amplified exons of the patient's TTR gene revealed a point mutation resulting in a substitution of leucine for valine at position 30. As the mutation creates a Cfr13I site, it was confirmed by PCR and restriction analysis. Our finding indicates the importance of position 30 in TTR-derived amyloid fibril formation.

Amyloidosis↗

PubMed1992

[Dynamic 3DFT FISP MR imaging of hepatocellular carcinoma].

Dynamic 3 dimensional Fourier transformation (3DFT) FISP MR imaging was performed in 5 patients with hepatocellular carcinoma before partial hepatectomy. Immediately after 0.1 mmol/kg of Gd-DTPA was administered intravenously, 3DFT FISP images (TR/TE/flip angle/slice thickness, 20 msec/8 msec/30 degrees/2-4 mm) were obtained every 30 seconds until 150 sec. We correlated dynamic MR images of the 5 patients with gross and microscopic findings. Some regions in the tumor corresponding to viable cells showed high intensity enhancement and other regions corresponding to necrotic regions showed no enhancement on the early phase images. We concluded that dynamic 3DFT FISP MR imaging which had good spatial resolution was useful in evaluating the vascularity of the tumor.

Aged↗

PubMed1992

Cytogenetic and clinical findings of myelodysplastic syndromes with a poor prognosis. An experience with 97 cases.

BACKGROUND: Clinical and cytogenetic analyses were performed in 97 patients with myelodysplastic syndromes (MDS) to evaluate risk factors for poor prognosis. METHODS/RESULTS: Among them, 22 patients survived for less than 1 year: 10 of these had complex chromosomal abnormalities (complex aberrations), but only 5 of the remaining 75 patients who survived longer than 12 months did. Leukemia did not develop in approximately half of the patients who died within 1 year. The occurrence rate of leukemic transformation appears to depend on MDS subtypes rather than cytogenetic changes. In contrast, the percentage of patients who survived for less than 1 year is related to chromosomal changes, especially to complex aberrations. Of particular interest in this study is that 7 of 11 patients with MDS who had myelofibrosis survived for less than 1 year, and 5 of 7 patients with secondary MDS were included in this group showing a poor prognosis. By hematologic analysis, significant differences were found in the hemoglobin values and platelet counts of patients who survived for less than 1 year. CONCLUSIONS: From this analysis, three major risk factors for a poor prognosis were identified: complex aberrations, a history of chemotherapy or radiation therapy (secondary MDS), and development of myelofibrosis. The survival probability in the patients with MDS having at least one of these three factors was significantly low when compared with that in patients without these factors, indicating that cytogenetic analysis in combination with observance of certain clinical manifestations is important in therapeutic management of patients with MDS.

Anemia, Refractory, with Excess of Blasts↗

PubMed1992

[Differentiation between hepatoma and hemangioma by inversion recovery snapshot FLASH MR imaging with variable TIs].

To differentiate hepatoma from hemangioma, MR studies were performed for 18 patients with 21 untreated liver tumors (hepatoma 10, hemangioma 11). We obtained inversion recovery snapshot FLASH images of liver tumors with variable TIs (50, 100, 150, 200, 250, 300, 400, and 500 msec). 8 hemangiomas showed higher intensity than liver parenchyma on the images at 150 msec and less of TI, and lower intensity at 200 msec or more TI. In 7, signal intensity of hepatoma became low at 150 msec or less of TI or remained high with prolonged TI. Inversion recovery snapshot FLASH imaging with variable TIs will be useful for differentiating between hepatoma and hemangioma.

Adult↗

PubMed1992

Sulfated alkyl oligosaccharides with potent inhibitory effects on human immunodeficiency virus infection.

Compounds with medium relative molecular masses active against human immunodeficiency virus (HIV) were synthesized. Sulfated alkyl oligosaccharides such as sulfated octadecyl maltohexaoside, sulfated dodecyl laminaripentaoside and sulfated dodecyl laminari-oligomer caused 50% inhibition of virus infection in the EC50 range of 0.4-0.7 microgram/mL in vitro using the MT-4 cell line and HIV-1HTLV-IIIB virus isolate, though sulfated oligosaccharides without alkyl groups showed low anti-HIV activities. This anti-HIV activity was close to the EC50 of 0.43 microgram/mL for a highly active sulfated polysaccharide curdlan sulfate which was reported to inhibit completely the HIV infection at a concentration as low as 3.3 micrograms/mL. These compounds were also active against HIV-2 and a clinically isolated HIV-1 with reduced AZT sensitivity. For such sulfated alkyl oligosaccharides, the mechanism of inhibition of HIV infection was assumed to be the inhibition of HIV binding to the cell and to some extent the interaction of the alkyl portion with the lipid bilayer of the virus.

Amino Acid Sequence↗

PubMed1992

A pSC101-par sequence-mediated study on the intracellular state of supercoiling of the pBR322 genome in Escherichia coli DNA topoisomerase I deletion mutant.

In Escherichia coli DNA topoisomerase I deletion mutant DM800, transcription of the tetracycline-resistance gene (tet) in the pBR322 genome is thought to create and maintain two domains of positive supercoils ahead, and negative supercoils behind, the transcription complex. To assess the actual intracellular state of twin-supercoiled domains, par sequence (365 bp) of plasmid pSC101, which shows a high affinity for DNA gyrase, was inserted into the EcoRI site upstream, or the AvaI site downstream, of the tet gene on the pBR322 genome. Analysis of the oxolinic acid-induced sites of cleavage by gyrase in DM800 revealed that the pBR322 derivatives are highly preferentially cleaved at the par sequence of the EcoRI site as well as the AvaI site and efficiently linearized when compared with pBR322. Assessment of the state of negative supercoiling of the pBR322 derivatives isolated suggested that the DNA (containing the AvaI site) ahead of the tet transcripts, is not so positively supercoiled and preferential interaction of gyrase with the EcoRI-par sequence does not result in removing negative superhelical turns so effectively as DNA topoisomerase I does on pBR322 DNA in the isogenic wild-type cells.

Base Sequence↗

PubMed1992

Slope of the end-systolic pressure-volume relation derived from single beat analysis is not always sensitive to positive inotropic stimuli in humans.

Single beat estimation of the slope of the end-systolic pressure-volume relation assumes symmetric left ventricular pressure increase and decay and requires extrapolation of peak isovolumic developed pressure (Pmax) from the left ventricular pressure curve of an ejection contraction. To test the sensitivity of this slope to positive inotropic stimuli, biplane cineangiocardiography and simultaneous high-fidelity left ventricular pressure measurements were performed in 50 patients with heart disease. The end-systolic pressure-volume relations were assessed under baseline conditions and during norepinephrine infusion (n = 19) or after postextrasystolic potentiation (n = 24), or both (n = 7). Norepinephrine did not change left ventricular end-systolic volume despite significant elevations of end-systolic pressure. Postextrasystolic potentiation significantly decreased end-systolic volume in association with an unaltered left ventricular end-systolic pressure. The potentiation significantly decreased the pressure half-time of contraction, an index of the speed of the left ventricular pressure increase, while it increased the pressure half-time of relaxation, an index of the speed of the pressure decline, indicating asymmetric pressure increase and decay. The slope of the end-systolic pressure-volume relation increased from 3.3 to 4.4 mm Hg/ml/m2 (p less than 0.001) during norepinephrine infusion. In contrast, despite an augmented contractility, the slope decreased significantly from 3.2 to 2.4 mm Hg/ml/m2 (p less than 0.0001) after the potentiation. The slope showed a high correlation with Pmax (r = 0.86, p less than 0.0001, n = 107). Thus, the slope of the end-systolic pressure-volume relation derived from single beat analysis is not always sensitive to inotropic interventions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Purification of factor XIa inhibitor from human platelets.

An inhibitor of activated factor XI (FXIa) in human platelets was recently identified as an amyloid beta-protein precursor (APP). We purified an FXIa inhibitor (XIaI) from the supernatant of activated human platelets, and assessed its inhibitor activity toward FXIa amidolytic activity. Approximately 90 micrograms of XIaI that cross-reacted with anti-APP antibody was obtained from two hundred units of platelet suspension by employing a six-step column chromatography procedure. The molecular weight of the purified XIaI was 94,000. The Ki value of XIaI to factor XIa was 526 +/- 120 pM, and the inhibition was enhanced by the addition of ZnCl2. The amino-terminal sequence of XIaI was L-E-V-P-T-D-G-N-A-, which is identical to that for the leucine (N18) to alanine (N26) sequence of APP751 and the amino-terminal sequence of protease nexin-2.

Amino Acid Sequence↗

PubMed1992

Identification of two enhancer elements in the gene encoding the type 1 glucose transporter from the mouse which are responsive to serum, growth factor, and oncogenes.

The type 1 glucose transporter (GLUT1) gene encodes an integral membrane glycoprotein responsible for facilitating transfer of glucose across plasma membrane and is rapidly activated by serum, growth factors, and by oncogenic transformation. To elucidate the molecular mechanisms of regulation of GLUT1 gene expression, we isolated and characterized the mouse GLUT1 gene. DNA elements regulating transcription of the gene were analyzed in transient expression assays after transfection of NIH/3T3 cells with a low background chloramphenicol acetyltransferase (CAT) vector system pSVOOCAT. We identified two enhancer elements; the first one is located 2.7 kilobases upstream of the cap site of the gene which contains the homologous sequences with two 12-O-tetradecanoylphorbol-13-acetate-responsive elements (TREs), a serum response element, a cyclic AMP-responsive element (CRE) and three GC boxes, and the second one is located in the second intron of the gene which contains the homologous sequences with two TREs and one CRE. With the promoter alone the transcription of the gene is activated by src, only slightly activated by ras and is not activated by serum and platelet-derived growth factor. When the gene is accompanied by one of these enhancers, the transcription is activated by all these stimuli.

3T3 Cells↗

PubMed1992

[Regenerating nodules in liver cirrhosis--patho-MR-serological correlation study].

An MR study was performed in 73 clinically diagnosed cirrhotic patients to determine correlations among the demonstration of small low intensity nodules (SLINs), secondary changes due to cirrhosis, and serological data. In 32 patients, liver cirrhosis was proved histologically. SLINs were observed in 38 of the 73 patients on gradient echo (GRE) images and in 28 patients on T2-weighted SE images. Patho-MR correlation study of the liver in the 32 histologically proved cirrhotic patients revealed that SLINs were seen on GRE images only in patients with iron deposits in regenerating nodules (RNs). There was no significant correlation between secondary changes due to liver cirrhosis and the demonstration of SLINs. Serological data indicating liver cell injury and iron store in the body were significantly higher in patients with iron deposits in RNs than in those without iron deposits.

Adult↗

PubMed1992

Site-specific antibodies directed against G protein beta and gamma subunits: effects on alpha and beta gamma subunit interaction.

Little is known about the specific domains of G protein beta and gamma subunits which interact with each other and with the alpha subunit. We used site-specific anti-peptide antibodies directed against beta and gamma subunits to investigate domains on beta and gamma subunits involved in alpha subunit interaction. Antibodies included four against the transducin (Gt) beta subunit (residues 1-10 = MS, 127-136 = KT, 256-265 = RA, and 330-340 = SW) and two against the gamma subunit (residues 2-12 = PV and 58-68 = PE). All antisera, when affinity-purified on peptide columns, yielded antibodies capable of recognizing the denatured cognate subunit on immunoblots, but only RA, SW, PV, and PE recognized native beta gamma t subunits. Affinity purification of MS and KT antisera on columns of immobilized native Gt yielded antibodies capable of recognizing native beta gamma t subunits. The functional effects of each antibody preparation on alpha t-beta gamma t interaction were assessed by assaying the ability of the preparations to immunoprecipitate beta gamma t subunits in the presence of excess alpha subunits and by testing the inhibition of beta gamma t-dependent ADP-ribosylation of alpha t-subunits catalyzed by pertussis toxin. On the basis of the results, we conclude that the domains on beta gamma t which may be directly involved in alpha t-beta gamma t interaction include the extreme amino terminus, residues 127-136 and 256-265 of beta t, and the carboxyl terminus of gamma t.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Diphosphate Ribose↗

PubMed1992

A novel transthyretin mutation associated with familial amyloidotic polyneuropathy.

We characterized the mutation associated with familial amyloidotic polyneuropathy in a Japanese patient. Sequence analysis of polymerase chain reaction-amplified exons of the transthyretin gene revealed a novel point mutation resulting in a substitution of arginine for glycine at position 47. The mutation was confirmed using allele-specific olgonucleotide hybridization procedures. This most likely represents a de novo mutation since neither parent carries the mutant allele.

Adult↗

PubMed1992

Familial amyloidotic polyneuropathy: report of patients heterozygous for the transthyretin Gly42 gene.

We studied 2 patients from a Japanese family with familial amyloidotic polyneuropathy (FAP). Their clinical features are similar to type 1 FAP, and the proband's rectal tissue contained amyloid that stained with antihuman transthyretin (TTR) antiserum. Direct DNA sequencing of the proband's TTR gene revealed a guanine-for-adenine substitution in the second base of codon 42, producing a glycine for glutamate substitution in the plasma protein.

Adult↗