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Biomedical subjects

M Sumi

Publications and source records attributed to M Sumi.

At least 127 records · Page 7Linked to original sources
PubMed1990

The osteogenetic potential of fracture haematoma. Subperiosteal and intramuscular transplantation of the haematoma.

We studied the precise role of the fracture haematoma in healing by the experimental transplantation of the haematoma at two days and four days after fracture of the rat femur to subperiosteal and intramuscular sites. We used bone marrow and peripheral blood haematomas for control experiments. The transplanted two-day fracture haematoma produced new bone by endochondral ossification at the subperiosteal site, but not at the intramuscular site. Four-day fracture haematoma produced new bone formation at both subperiosteal and intramuscular sites. These results suggest that fracture haematoma has an inherent osteogenetic potential.

Animals↗
PubMed1989

A spider toxin (JSTX) inhibits L-glutamate uptake by rat brain synaptosomes.

Joro spider toxin (JSTX), a specific blocker of glutamate receptors, was found to exert a prominent suppressive action on the Na+-dependent binding of L-glutamate to synaptic membranes and on glutamate uptake by synaptosomes in a dose-dependent manner. In contrast, the synthesized 2,4-dihydroxyphenylacetylasparagine (2,4-DHPA-ASN), a common moiety of spider toxins, which has been shown to exhibit almost the same activity as intact JSTX with respect to the inhibition of Na+-independent glutamate binding to its synaptic membrane receptors, shows lower potency in inhibiting Na+-dependent binding and uptake of L-glutamate. From these findings, it is clear that JSTX has the ability to inhibit not only L-glutamate binding to its synaptic membrane receptors but also L-glutamate uptake by synaptosomes, and that polyamines linked to 2,4-DHPA-ASN in the molecule of spider toxins may participate in the inhibition of L-glutamate uptake.

Animals↗
PubMed1989

[Double-blind comparative study of roxithromycin (RU 28965) and midecamycin acetate (MOM) in the treatment of pneumonia].

The clinical efficacy and safety of Roxithromycin (RU) were compared with those of Midecamycin acetate (MOM) in patients with pneumonia in a double blind study. RU and MOM were administered orally for 14 days with daily doses of 300 mg (150 mg b.i.d.) and 600 mg (200 mg t.i.d.), respectively. The following results were obtained. 1. RU and MOM were administered to a total of 204 patients (RU: 101, MOM: 103). The clinical efficacy was judged in 150 patients (RU: 70, MOM: 80), with 54 of the patients excluded from the total by the committee. 2. The clinical efficacy rates were 81.4% for RU and 70.0% for MOM on the basis of the committee's judgement. There was no significant difference between the two groups. In the evaluation of the clinical efficacy by the doctors in charge, the efficacy rates were 81.4% for RU and 67.5% for MOM, which constitutes a significant difference between the two groups (p less than 0.05). 3. No significant difference was found between the two drugs in bacteriological efficacy. 4. No significant differences were observed in either the incidence of side effects between RU (4.3%) and MOM (4.0%) or in abnormal changes in the laboratory findings. 5. Regarding the clinical usefulness judged by the committee, RU showed a significantly higher rate than MOM (79.2% vs. 67.9%). There was no significant difference in the judgement by the doctors in charge. From the above results, it was concluded that a daily dosage of 300 mg of RU was equal in usefulness to 600 mg daily of MOM in the treatment of mild to moderate pneumonia.

Adolescent↗
PubMed1989

5-Fluorouracil derivatives with serum protein binding potencies.

To develop an optimal delivery system for 5-fluorouracil (5FU) using serum protein as a drug carrier, a series of its benzyl derivatives was synthesized. Then their binding to the serum protein was investigated by equilibrium dialysis. The benzyl derivatives of 5FU were strongly bound to rat plasma protein or human serum albumin. The bound percentage increased with increasing hydrophobicity. It was suggested that the benzyl derivative of 5FU existed in the blood as a complex with serum albumin and circulated for a long time as a polymeric drug does.

Animals↗
PubMed1988

The P wave in the magnetocardiogram.

The P wave of the magnetocardiogram (MCG) was investigated in normal subjects and in patients with right and left atrial overloading. In normal subjects, the MCG P wave was positive at right lower sternal sites and negative in the other portions. The current source deduced from the MCG and the isomagnetic map was directed inferiorly and to the left throughout the entire phase of atrial activation. In patients with right atrial overloading, the direction of the current source deduced from the MCG was similar to that of normal subjects, but its amplitude was significantly greater. In left atrial overloadings, a negative-positive biphasic P wave was seen more frequently than in normal subjects at left parasternal sites. In the late phase of atrial activation, the MCG could detect the two dipoles, i.e. one directed inferiorly and other directed to the left. These dipoles might correspond to right and left atrial activities, respectively. These results show that the MCG might add useful information on current source to the conventional electrocardiogram.

Adult↗
PubMed1988

Analysis of the T wave of the magnetocardiogram in patients with essential hypertension by means of isomagnetic and vector arrow maps.

Magnetocardiograms (MCGs) of 50 normal subjects and 40 patients with essential hypertension were recorded to determine the value of the MCG for detecting abnormal repolarization. Among the patients with essential hypertension, there were nine cases (22.5%) in whom isopotential maps did not show rightward repolarization vectors but isomagnetic and vector arrow maps showed a rightward repolarization vector in some areas in addition to the normal repolarization vector. Departure maps of the ECG showed an increased repolarization vector directed anteriorly in some of these cases. The repolarization abnormality was recognized in only the MCG departure map in four cases, while no case showed abnormality in only the ECG departure map. With the progress of hypertension, the repolarization abnormality was seen more frequently and its detection using the MCG was higher than that using the ECG. Furthermore, multiple dipoles were detected more frequently from the MCG than from the ECG. Thus the MCG seems more useful than the ECG in the analysis of repolarization abnormalities in essential hypertension.

Adult↗
PubMed1988

Rokitamycin uptake by alveolar macrophages.

The ability of antibiotics to enter cells, especially phagocytic cells, may be an important factor affecting therapy for infections caused by organisms which survive and proliferate intracellularly. It is well known that macrolides and clindamycin have high intracellular penetration ability. We studied the uptake of rokitamycin (RKM), a new oral macrolide, using rabbit alveolar macrophages and 2 other macrolides for comparison. Intracellular concentrations of erythromycin and josamycin were, respectively, approximately 20 and 40 times higher than extracellular concentrations when they were incubated at an initial extracellular concentration of 5 micrograms/ml (I/E = 20.1 +/- 2.6, 40.8 +/- 7.4). In comparison to these 2 macrolides, the uptake of RKM was massive and very rapid. The cellular concentration of RKM was approximately 120 times higher than the extracellular concentration. Uptake of the 3 macrolides by rabbit alveolar macrophages at 4 degrees C was approximately 10% of that at 37 degrees C. This study demonstrated that RKM was rapidly and massively accumulated by alveolar macrophages, and that the drug accumulation depends on temperature. These observations suggest that RKM therapy may be very effective for the treatment of some infectious diseases.

Animals↗
PubMed1987

Inhibitory effect of 2,4-dihydroxyphenylacetylasparagine, a common moiety of spider toxin, on glutamate binding to rat brain synaptic membranes.

2,4-Dihydroxyphenylacetylasparagine (2,4-DHPA-ASN), a common moiety of molecules of spider toxins, was shown to inhibit L-[3H]glutamic acid binding to rat brain synaptic membranes in a dose-dependent manner. The inhibitory effect of 2,4-DHPA-ASN was almost the same as that of intact spider toxin isolated from Nephila clavata, but significantly higher than that of 2,4-dihydroxyphenylacetic acid (2,4-DHPA). In addition, neither 2,4-dihydroxybenzoic acid nor the isomers of 2,4-DHPA suppressed the glutamate binding. These results suggested that 2,4-DHPA might be the functional part and asparagine in the molecules of spider toxins seemed to cause increasing affinity toward the recognition site of glutamate binding.

Animals↗
PubMed1987

Phosphatidylinositol stimulates phosphorylation of protein components I and II in rod outer segments of frog photoreceptors.

We studied the effect of phosphoinositides on the phosphorylation of endogenous proteins in the soluble fraction of the frog photoreceptor rod outer segments (ROS). Phosphatidylinositol (PI) stimulated the phosphorylation of two low molecular weight proteins, components I and II (12 and 11 kDa) which are known to be the preferential substrates of the cyclic GMP (cGMP)-dependent protein kinase in the ROS. Polyphosphoinositides (PPI) specifically inhibited the PI-dependent phosphorylation of these two components. On the other hand, PPI stimulated the phosphorylation of 38, 48 and 52 kDa proteins in the absence of PI. These data suggest that PI and PPI may function in the ROS by regulating the phosphorylation of some enzymes or regulator proteins in the transduction mechanism in the ROS.

Adenosine Triphosphate↗
PubMed1987

Pharmacokinetic study of carbamazepine and its epoxide metabolite in humans.

A major metabolite of carbamazepine (CBZ), CBZ-10, 11-epoxide (EPO), has been reported to possess anticonvulsant properties. Therefore, the present study was undertaken in order to develop a pharmacokinetic model to predict the behavior of EPO in the body after administration of CBZ. The serum concentration-time curves after oral administration of solution of CBZ (200 mg) or EPO (150 mg) in six healthy subjects showed the characteristic "nose", suggesting that disposition of CBZ or EPO could be described by the two-compartment model. The kinetic parameters of disposition for CBZ and EPO were calculated by the method of Wagner, assuming the absolute bioavailabilities of CBZ and EPO to be 1.0 and 0.81, respectively. Total body clearance and elimination rate constant of EPO were very much larger than those of the parent drug but there was no statistically significant difference in the distribution volume between CBZ and EPO. The formation rate of EPO was calculated by a deconvolution method, and obeyed Michaelis-Menten kinetics. Based on these findings, a pharmacokinetic model of the fate of CBZ and EPO in humans was developed and the time courses of CBZ and EPO in serum after oral administration of three tablet preparations and a solution containing 200 mg of CBZ were simultaneously fitted to this model by solving the differential equations by the Runge-Kutta-Gill method. There was good agreement between calculated and observed serum values, suggesting that the present model is appropriate to describe the formation and disposition of EPO from CBZ. The formation rate constant of EPO (Vmax/Km/V1) was approximately one-fifteenth of the elimination rate constant of EPO. This suggested a flip-flop model in which the formation of EPO was rate-limiting in humans. The observation that the serum concentrations of EPO after administration of CBZ were one-tenth to one-twentieth of those of the parent drug was well explained by the flip-flop kinetics of EPO, together with the large differences in total body clearance and elimination rate constant between CBZ and EPO.

Adult↗
PubMed1987

New synthetic quinolone antibacterial agents and serum concentration of theophylline.

The effect of pipemidic acid and five new synthetic antibacterial agents--norfloxacin, enoxacin, ofloxacin, ciprofloxacin, and pefloxacin--on the serum level of theophylline was studied in healthy male adult volunteers after concomitant oral administration of these agents with a slow release preparation of theophylline. The results indicated that enoxacin, ciprofloxacin, and pipemidic acid might decrease the clearance of theophylline in the liver, and the attention should be paid in clinical use when enoxacin or pipemidic acid is coadministered with theophylline.

Adult↗
PubMed1987

Concentrations of superoxide dismutase and superoxide anion in blood of patients with respiratory infections and compromised immune systems.

To investigate the involvement of oxygen free radicals and their scavenger systems in the defenses of compromised hosts against pulmonary infections, we determined superoxide anion (SOA) and superoxide dismutase (SOD; EC 1.15.1.1) concentrations in the blood of compromised hosts and noncompromised hosts, with or without pneumonia. In the compromised hosts without pneumonia (compromised controls), SOD concentrations were lower than in noncompromised hosts (healthy controls). However SOA values in compromised controls did not differ statistically from that in healthy controls. Similar changes were observed in noncompromised hosts with pneumonia. In compromised hosts with pneumonia, SOD concentrations were further decreased by pulmonary infections. By contrast, SOA values were increased in pneumonia. There were, however, no differences in the values for ceruloplasmin among all the groups. The values for alpha 2-macroglobulin and alpha1-antitrypsin were within normal limits in compromised controls but were greater in compromised hosts with pneumonia. These results suggest that a decreased activity concentration of SOD in compromised controls may be partly responsible for the depression of the host's immune defenses.

Adult↗