Search PubMed⌕ Search

Biomedical subjects

T Miyasaka

Publications and source records attributed to T Miyasaka.

At least 55 records · Page 3Linked to original sources
PubMed1996

[An application of semiquantitative analysis of pulmonary scintigram to pulmonary tuberculosis sequelae].

We performed ventilation-perfusion scintigraphy in 13 patients with pulmonary tuberculosis sequelae and 21 with chronic obstructive pulmonary disease. We used 99mTc-MAA for perfusion scintigram and 133Xe gas for ventilation scintigram. We added the radioactivities during the rebreathing phase of the ventilation scintigram to make a computerized image of the lung volume. Regions of interest (ROIs) were derived from radioactivities on each image. ROIs included each whole lung on lung volume (L) image and areas where radioactivity was greater than 70% of the highest radioactivity on perfusion (P70) image. We counted the area of ROIs on L and P70, and used the ratio of perfusion to lung volume (P70/L) as a parameter of pulmonary perfusion. P70/L in patients with pulmonary tuberculosis sequelae was significantly higher than that in those with COPD. This suggested that the area of high pulmonary perfusion is larger in the patients with pulmonary tuberculosis sequelae as compared with those with COPD.

Aged↗
PubMed1996

[Chronic eosinophilic pneumonia involving eosinophil cationic protein and bone marrow cells].

A 64-year-old women presented with a dry cough. The common cold was diagnosed and she was given medication, but the symptom did not resolve. She came to our hospital, and multiple patchy shadows were seen on a chest X-ray film. Bronchoalveolar lavage fluid contained an abnormally high percentage of eosinophils. Microscopic examination of transbronchial lung biopsy specimens showed infiltration of eosinophils into the alveoli and alveolar septa. Chronic eosinophilic pneumonia was diagnosed. Analysis of bone marrow cells showed high percentages of mature eosinophilic cells, and blood serum had a high concentration of eosinophil cationic protein. An inhalation challenge test with methacholine revealed bronchial hypersensitivity and hyperresponsiveness. Prednisolone (30 mg/day) was given and the symptoms resolved. After steroid treatment, the patient was asymptomatic, although airway hyperresponsiveness remained. The concentration of eosinophil cationic protein in serum and the results of the methacholine inhalation test reflected the degree of chronic eosinophilic pneumonia, and the production of eosinophils in bone marrow was suppressed by steroid medication.

Blood Proteins↗
PubMed1996

[Detectability of simulated nodules on chest phantom by Fuji computed radiography: comparison of different nodule sizes, configurations and tube voltages].

The detectability of simulated nodules placed on a chest phantom and shown on FCR images has been studied. Different tube voltages (130 kVp, 100 kVp), presence or absence of compensation filter, various sites and different sizes (5 mm/10 mm) and configurations (spherical or broad based) of the nodule were examined. 112 FCR chest phantom images were evaluated by ten radiology specialists utilizing ROC analysis. The detection rate for nodules was influenced in general by the site. The detection rate was as follows in decreasing order: intercostal, overlaid with one rib, two ribs, diaphragm and heart. Detection of nodules of 10 mm in height was mainly influenced by the density of the lung where the nodule was located, whereas that of nodules of 5 mm in height was more dependent on the site of the nodule, probably greatly influenced by the amount of structure mottle. Spherical nodules of 5 mm in height were more frequently recognized than the broad-based ones. High kVp (130 kVp) resulted in a higher detection rate for both sizes of nodules than low kVp (100 kVp). Detection of spherical nodules overlying the heart or diaphragm was improved with the use of a compensation filter.

Humans↗
PubMed1995

Synthesis and antiviral activity of 6-benzyl analogs of 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT) as potent and selective anti-HIV-1 agents.

Several 6-benzyl analogs of 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (1; HEPT) were synthesized and evaluated for their anti-HIV-1 activity. LDA (lithium diisopropylamide) lithiation of 5-ethyluracil derivatives 7 and 8 and subsequent reaction with an aryl aldehyde gave 6-(arylhydroxymethyl)-5-ethyluracil derivatives 9-12. 6-(Arylhydroxymethyl)-5-isopropyluracil derivatives 15-18 were prepared from the 5-isopropyl-2-thiouracil derivatives 13 and 14 by the above procedure following oxidative hydrolysis of the thione. Preparation of the target 5-alkyl-1-(alkoxymethyl)-6-benzyluracil derivatives 27-34 was carried out by acetylation of 9-14 followed by Pd-catalyzed hydrogenolysis. The 1-butyl- (37 and 39) and 1-(2-methoxyl)- (38 and 40) 5-alkyl-6-benzyluracils were synthesized by 1-alkylation of the 3-phenacyl derivatives 35 and 36 with alkyl halides followed by deprotection of the 3-phenacyl group. Compounds synthesized in this study inhibited HIV-1 replication in MT-4 cells in the submicromolar to namomolar concentration range. From this series of compounds, 6-benzyl-1-(ethoxymethyl)-5-isopropyluracil (33) was selected for clinical evaluation.

Animals↗
PubMed1995

Radiographic factors predicting non-union of displaced intracapsular femoral neck fractures.

After 82 patients underwent osteosynthesis with multiple pinning for a displaced intracapsular femoral neck fracture, 58 fractures were united, and 24 were not. These 82 patients were included in a discriminant analysis. Union and non-union groups were the dependent variables. Eleven presumably predictive factors measured on X-ray films obtained from these patients before and immediately after operation were taken as independent variables. Three radiographic factors were selected by a stepwise method according to the effect they had on union. These were: the distance of medial displacement between fragments before reduction; the varus angle after reduction; and the distance of medial displacement between fragments after reduction. The distance of medial displacement between fragments before reduction proved the most important factor in making a choice between osteosynthesis and primary arthroplasty, and it was revealed that osteosynthesis could not be expected to provide union if the distance was 20 mm or more. It was also confirmed that union was promoted, if the cranial fragment was reduced to a valgus position and the medial cortical bones were aligned as much as possible at the time of osteosynthesis.

Aged↗
PubMed1995

[Changes of masticatory muscle activity after surgical orthodontic treatment for skeletal mandibular protrusion].

The purpose of this study was to analyze the recovery process of masticatory muscle activity after mandibular set-back osteotomy. The subjects were 11 adult patients with skeletal mandibular protrusion. They received surgical orthodontic treatment and attained a stable occlusion. E. M. G. recordings of clenching and habitual jaw movement were taken from the temporalis anterior, posterior, and masseter muscles with surface electrodes before preoperative orthodontic treatment just before surgery, and 6 months, 1 year and over 5 years after surgery. The parameters of E. M. G. analysis were 70% of the maximum voltage, the buildup time from the onset of activity to 70% of the maximum voltage and the time difference of the onset of activity in reference muscles. The results were as follows: 1. The initial level of E. M. G. activity was related to the rate of recovery following surgery. 2. Differences in masticatory muscle activity were reflected in the activity levels of the respective muscles during the recovery period. 3. A fairly complete recovery of E. M. G. activity was attained about ten months after surgery. 4. The time from the onset of activity to attaining 70% of the maximum voltage became progressively shorter. 5. The time difference of the onset of activity in reference to muscles decreased. It was I concluded that masticatory muscle activity could well adapt to the newly surgically-established maxillomandibular skeletal relationship.

Adolescent↗
PubMed1994

[Study of X-ray filter and peak kilovoltage in Fuji Computed Radiography in regard to the detection of simulated pulmonary nodules].

To determine a suitable combination of X-ray filter and tube kilovoltage for Fuji Computed Radiography (FCR), to provide better detection of pulmonary nodules and reduce patient exposure, we compared observer performance with different X-ray filters and tube voltages. Radiographs were obtained with a copper filter backed by aluminium, with a tungsten filter backed by yttrium and aluminium, and with a lead filter backed by yttrium and aluminium, at both 100 kVp and 135 kVp. Observer performance in detecting simulated lung nodules, which were placed on the posterior aspect of a chest phantom, was compared using receiver operating characteristic (ROC) techniques for each combination of the X-ray filter and tube voltage. The results of the study indicated that 1) nodule detection was superior for the images obtained with 135 kVp as compared with 100 kVp; 2) approximately equal detection rates were obtained for the three X-ray filter sets, although results with the tungsten filter were slightly inferior to the other two filters; and 3) the absorbed dose may be reduced by 30% with the use of a lead filter backed by yttrium and aluminium compared with a copper filter backed by aluminium. We conclude that chest radiography with FCR should preferably be conducted with a higher kilovoltage, e.g., 135 kVp rather than 100 kVp, to ensure a higher detection rate of pulmonary nodules and in conjunction with a lead filter backed by yttrium and aluminium to reduce X-ray exposure to the patient.

Filtration↗
PubMed1994

Preclinical evaluation of MKC-442, a highly potent and specific inhibitor of human immunodeficiency virus type 1 in vitro.

MKC-442 (6-benzyl-1-ethoxymethyl-5-isopropyluracil or I-EBU) has recently been identified as a highly potent and specific inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase. Since the compound has favorable pharmacokinetic and toxicity profiles in vivo, we have evaluated MKC-442 for its inhibitory effect on the replication of HIV-1 in various cell cultures, including human peripheral blood lymphocytes and monocyte-macrophages. The 50 and 90% effective concentrations for HIV-1 (HTLV-IIIB strain) replication in MT-4 cells were 15 and 98 nM, respectively. MKC-442 was also inhibitory to HIV-1 replication in peripheral blood lymphocytes and monocyte-macrophages as determined by the production of p24 antigens in the culture supernatant. Fluorescence-activated cell sorter analysis revealed that MKC-442 was equally active against zidovudine-resistant mutants and zidovudine-susceptible strains. Furthermore, combinations of MKC-442 with either 3'-azido-3'-deoxythymidine, 2',3'-dideoxycytidine, or 2',3'-dideoxyinosine synergistically inhibited the replication of HIV-1. Thus, MKC-442 has been considered as a candidate for clinical efficacy studies.

Antiviral Agents↗
PubMed1994

Synthesis and antitumor activity of 20(S)-camptothecin derivatives. A-ring-substituted 7-ethylcamptothecins and their E-ring-modified water-soluble derivatives.

Twenty-six novel A-ring-modified 7-ethylcamptothecins (6) were synthesized by Friedländer's condensation of the chiral tricyclic ketone (5) with aminopropiophenones (4). The compounds substituted with fluorine at the 11 position showed strong cytotoxicity to KB and L1210 cells. The 11-fluoro derivatives also exhibited strong inhibitory activity on DNA topoisomerase I. Nine compounds 6 with four to ten times stronger cytotoxicity than that of camptothecin were selected and converted into water-soluble 17-O-acyl amide derivatives (8). Compounds 8e (10-Me, O-COCH2CH2SCH3) and 8f (11-F, O-COC2H5) showed activity towards Meth A in mice that was comparable to that of CPT-11, at lower doses than CPT-11.

Animals↗
PubMed1993

Synthesis and antibacterial activity of a new series of tetracyclic pyridone carboxylic acids.

A novel tetracyclic pyridone carboxylic acid with a thiazolidine ring, 1,2-dihydro-9,1-(epoxymethano)-7-fluoro-8-(4-methyl-1-piperazinyl)-5-oxo -5H- thiazolo[3,2-a]quinoline-4-carboxylic acid (4a), and variants with a nitrogen atom (4b) or carbonyl group (4c) in the place of the 10-position oxygen atom of 4a were prepared and tested for antibacterial activity and inhibitory activity on DNA gyrase from Escherichia coli KL-16. The in vitro antibacterial potency with regard to the 10-position atom was found to be of the following order; O > NCH3 = C = O. The IC50 values for DNA gyrase inhibition activity for the 4a, 4b, and 4c compounds were 0.33, 0.53, and 0.67 g/mL, respectively. The activity of 4a, in which the C-3 methyl group and C-5 of ofloxacin (2a) were connected with a sulfur atom to restrict the conformation of 2a, was more potent than that of 2a against both Gram-positive and -negative bacteria, except for Pseudomonas aeruginosa. Compared to the tetracyclic pyridone carboxylic acid 1a, which has a flat thiazole ring, compound 4a showed comparable or slightly more potent activity against both Gram-positive and -negative bacteria, except for P. aeruginosa.

Anti-Infective Agents↗
PubMed1993

Effect of human serum on the in vitro anti-HIV-1 activity of 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT) derivatives as related to their lipophilicity and serum protein binding.

Several derivatives of 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT) were examined for their inhibitory effects on the replication of human immunodeficiency virus type 1 (HIV-1) in MT-4 cells in the presence of various concentrations (10-50%) of human serum (HS). Although all HEPT derivatives proved to be highly potent inhibitors of HIV-1 in the presence of 10% fetal bovine serum, some of them were less inhibitory to HIV-1 replication in the presence of HS. The HEPT derivatives were found to be highly bound to HS proteins. Both the anti-HIV-1 activity and HS protein binding of the compounds appeared to be related to their lipophilicity.

Acetylcysteine↗
PubMed1993

Chemical modification of an antitumor alkaloid, 20(S)-camptothecin: E-lactone ring-modified water-soluble derivatives of 7-ethylcamptothecin.

7-Ethylcamptothecin (1d), a model which does not have any site on the A-ring for further modification was converted into water-soluble derivatives by opening the E-ring lactone. 1d was heated in N,N-dimethylenediamine to yield amide 2a, and this was then acylated to furnish 3a-q, which were soluble in water as their HCl salts. The propionyl (3b), butyryl (3c) and methylthiopropionyl (3h) derivatives showed higher activity than the sodium salt of 1d. The acyl group makes the derivatives more lipophilic, and ease of hydrolysis of amide 2a to 1d is thought to be necessary for significant activity.

Animals↗
PubMed1993

Chemical modification of antitumor alkaloids, 20(S)-camptothecin and 7-ethylcamptothecin: reaction of the E-lactone ring portion with hydrazine hydrate.

The structure of the N-amino pyridone (4a) obtained by the reaction of camptothecin (1a) with hydrazine was determined by X-ray crystallography. A mixture of 7-ethylcamptothecin (1b) and hydrazine hydrate was stirred at room temperature, and the hydrazide (2b) was isolated as its diacetate 2c. Treatment of the 17-O-acetyl amide (5a) with hydrazine gave 1b (74% yield) and the N-amino lactam 6 (11% yield). Compounds with bulky acyl groups, 5c--e, gave 6 in modest yields. The N-amino lactam 6 was smoothly dehydrated into the pyridone 4d by refluxing in hydrazine hydrate.

Animals↗
PubMed1993

Stereo-controlled C-C bond formation at the anomeric position of uracil nucleosides.

Stereoselective synthesis of 1'-carbon-substituted uracil nucleosides has been achieved through face-selective bromo-pivaloyloxylation of a 1',2'-unsaturated derivative and successive SnCl4-promoted nucleophilic substitution with organosilicon reagents. This constitutes the first example of C-C bond formation at the anomeric position of nucleosides.

Carbon↗
PubMed1992

Synthesis and antiviral activity of deoxy analogs of 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT) as potent and selective anti-HIV-1 agents.

The effect of substitution in the acyclic structure of 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)-thymine (HEPT) on anti-HIV-1 activity was investigated by synthesizing a series of deoxy analogs and related compounds. Preparation of 1-[(2-alkyloxyethoxy)methyl]-6- (phenylthio)thymine (2-4) derivatives was carried out based on alkylation of HEPT with primary alkyl halides. Preparation of the 1-[(alkyloxy)methyl]-6-(phenylthio)thymine (26-31) and 1-[(alkyloxy)methyl]-6-(arylthio)-2-thiouracil (32-45) derivatives was carried out on the basis of LDA lithiation of 1-[(alkyloxy)-methyl]thymine (9-14) and 1-[(alkyloxy)methyl]-2-thiouracil (15-25) followed by reaction with diaryl disulfides. The oxidative hydrolysis of the 2-thiouracil derivatives gave 1-[(alkyloxy)methyl]-6-(arylthio)uracil derivatives (46-57). 1-Alkyl-6-(phenylthio)thymine (59-61) derivatives were prepared on the basis of alkylation of 6-(phenylthio)thymine (58). Methylation of the hydroxyl group of HEPT did not affect the anti-HIV-1 activity of HEPT. Substitution of the 1-(2-hydroxyethoxy)methyl group by ethyl, butyl, methoxymethyl, (propyloxy)methyl, and (butyloxy)-methyl groups somewhat improved the original anti-HIV-1 activity of HEPT. Substitution with ethoxymethyl and (benzyloxy)methyl groups further potentiated the activity [EC50: 1-(ethoxy-methyl)-6-(phenylthio)thymine (27), 0.33 microM; 1-[(benzyloxy)methyl]-6-(phenylthio)thymine (31), 0.088 microM]. When the 5-methyl group of 27 and 31 was replaced by an ethyl or an isopropyl group, the anti-HIV-1 activity was improved remarkably [EC50: 5-ethyl-1-(ethoxymethyl)-6-(phenylthio)-uracil (46), 0.019 microM; 5-ethyl-1-[(benzyloxy)methyl]-6-(phenylthio)uracil (52), 0.0059 microM; 5-isopropyl-1-(ethoxymethyl)-6-(phenylthio)uracil (55), 0.012 microM; 5-isopropyl-1-[(benzyloxy)methyl]-6-(phenylthio)uracil (56), 0.0027 microM]. Introduction of two m-methyl groups into the phenylthio ring also potentiated the activity.

Antiviral Agents↗