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Biomedical subjects

M Samejima

Publications and source records attributed to M Samejima.

At least 37 records · Page 2Linked to original sources
PubMed1992

Right anterior caudocranial oblique projection for portal venography; its indications and advantages.

Right anterior caudocranial oblique (RACCO) projections were evaluated for transarterial portography with digital subtraction angiography. For RACCO projection, the image intensifier was tilted 25 degrees caudally and 30 degrees to the patient's right with the patient in the supine position. The abnormal findings imaged in 20 patients were analyzed by types of abnormalities and their locations in the portal venous systems by comparing RACCO and PA projections. The RACCO view was superior to the PA projection for demonstrating either encasements or tumor thrombi in relatively proximal segments of the portal venous branches. Two encasement lesions and a tumor thrombus were imaged only on the RACCO projection. However, the RACCO projection had no definite advantage over the PA view for showing encasements or tumor thrombi in the distal segmental branches. The RACCO projection was superior to the PA view for demonstrating defects in the hepatograms of some hepatic segments (S5 and S8). We concluded that the RACCO view is extremely useful and is indicated for angiographic work-ups of hepatic or biliary lesions when abnormalities are suspected in proximal portal venous branches.

Angiography, Digital Subtraction↗
PubMed1992

Gastric emptying rate of drug preparations. III. Effects of size of enteric micro-capsules with mean diameters ranging from 0.1 to 1.1 mm in man.

The gastric emptying rates of three enteric micro-capsule preparations with mean diameters of 1.1 mm and less (1.1, 0.5 and 0.1 mm) were compared. The gastric emptying rate was evaluated by determining the pharmacokinetic parameters of pyridoxic acid, including Vmax (peak excretion rate) and Tmax (time to reach peak excretion rate) after oral administration of micro-capsules containing pyridoxal phosphate as a marker drug to five healthy subjects. When given under fasting conditions, the gastric emptying rates of these preparations, according to Tmax, differed significantly; the preparations with smaller particle sizes were emptied from the stomach at a faster rate than those with larger particle sizes. However, under non-fasting conditions the gastric emptying rates were virtually the same, regardless of particle size, and all the preparations were emptied from the stomach at a much slower rate than when administered under fasting conditions.

Adult↗
PubMed1991

Mechanisms of redox interactions between lignin peroxidase and cellobiose:quinone oxidoreductase.

The mechanism of redox interactions between the heme-enzyme, lignin peroxidase (LiP), and the FAD-enzyme, cellobiose:quinone oxidoreductase (CBQ) (EC 1.1.5.1), was investigated under various conditions. Veratryl alcohol oxidation by LiP was inhibited by CBQ in the presence of cellobiose. Lineweaver-Burk plots at various CBQ concentrations suggest that this inhibition is non-competitive. The oxidation rate of the reduced CBQ (FADH2) by LiP plus H2O2 increased significantly only in the presence of veratryl alcohol. Furthermore, the cation radical derived from 1,2,4,5-tetramethoxybenzene was reduced by CBQ in the presence of cellobiose. It is concluded from these results that CBQ can reduce aromatic cation radicals and that veratryl alcohol acts as a radical mediator of the redox interactions between LiP and CBQ.

Carbohydrate Dehydrogenases↗
PubMed1991

Dissociation of photoreceptor cells from the pineal organ of the lamprey, Lampetra japonica.

Photoreceptor cells, nerve cells and supporting cells were dissociated from the pineal organ of the river lamprey, Lampetra japonica, by the use of 10 U/ml papain solution at 28 degrees C for 20 min, followed by repeated trituration. With the aid of Nomarski interference-contrast optics, photoreceptor cells, nerve cells and supporting cells were readily identified. Electron-microscopic examination revealed that isolated photoreceptor cells display an outer segment endowed with a few lamellar disks and connected to the inner segment (ellipsoid) via a connecting cilium. The structural features of the dissociated photoreceptor and supporting cells strongly resemble the morphology of the respective cellular elements in situ. We succeeded in culturing dissociated cells for time periods up to 48 h when the procedure described in detail was applied.

Animals↗
PubMed1990

[Transcatheter embolization therapy of pseudoaneurysms in patients with chronic pancreatitis].

Chronic pancreatitis is known to cause vascular disorders including pseudoaneurysm of peripancreatic arteries. Although the incidence of pseudoaneurysms due to pancreatitis detected by angiography has been reported as high as 10% in western literature, they are still considered rare in Japan. We reported two cases of pseudoaneurysm caused by chronic pancreatitis, one in splenic artery and the other in gastroduodenal artery, successfully treated by embolization. The embolizations were performed by occluding proximal splenic artery for splenic arterial aneurysm and gastroduodenal artery distal and proximal to the orifice for the aneurysm of gastroduodenal artery with stainless steel coils. Since the surgical therapy has high mortality rate, we consider transcatheter embolization is the treatment of choice for pseudoaneurysms caused by chronic pancreatitis.

Aneurysm↗
PubMed1990

[Right anterior caudo-cranial oblique (RACCO) view of portal branches].

The right caudocranial oblique (RACCO) view which is obtained by tilting the image intensifier 25 degrees caudally and 30 degrees to the right while the patients lie in supine position is proposed for improved depiction of the portal venous system. Transarterial portography with digital subtraction angiography was performed in the RACCO and posteroanterior (PA) views in 32 patients. Comparison of the two views revealed that the RACCO view was superior to the PA view of the left main branch in 25 patients (78%) and of the right posterior lobe branch in 24 (75%) patients. Visibility of more distal portal branches, however, did not always improve by RACCO view. RACCO view will be useful for the evaluation of portal systems of primary and secondary hepatic neoplasms as a special view following portogram in PA projection when more detailed information is necessary on proximal portal branches.

Angiography, Digital Subtraction↗
PubMed1990

[Pulmonary complication following intra-arterial infusion of lipiodol-adriamycin emulsion for hepatocellular carcinoma, report of a case].

A case of acute pulmonary complication following intra-arterial infusion of Lipiodol-Adriamycin emulsion for hepatocellular carcinoma was reported. Intra-arterial infusion chemotherapy was performed on a 75-year-old male with Lipiodol-Adriamycin emulsion (Lipiodol 8 ml + Adriamycin 40 mg). Severe dyspnea and cyanosis started about 30 minutes after the infusion, and blood gas analysis revealed hypoxemia and hypocapnia. Chest X-ray revealed diffuse infiltrative shadow throughout the both lungs. He was on positive end-expiratory pressure breathing for 4 days. Clinical symptoms and chest X-ray improved rapidly in the course of two weeks, he became almost asymptomatic. We concluded that the nature of this pulmonary damage was pulmonary edema due to the large amount of Adriamycin that flowed into pulmonary artery via arterio-venous shunt present in the hepatocellular carcinoma.

Aged↗
PubMed1990

Pharmacokinetic analysis of absorption and metabolism of dopamine and a dopamine prodrug in dogs.

Pharmacokinetic compartment models were constructed to describe the absorption and metabolism of dopamine (DA) and DA prodrug, N-(N-acetyl-L-methionyl)0,0-bis-eth-oxycarbonyl) dopamine(1). Plasma concentrations of DA, DA-SO4, and DOPAC after oral administration of DA to dogs, were analysed using the pharmacokinetic model assuming the contribution of first-pass metabolism for the formation of DA-SO4 and DOPAC. Though plasma concentration of DA was quite different from that of DA-SO4 or DOPAC, these data were simultaneously analysed with a good fitting curve. The apparent absorption rate constant of DA(K1) was proved to be much smaller than the apparent formation rate constants of DA-SO4(K2) or DOPAC(K3). It was found that the compartment model is useful for the evaluation of absorption and metabolic inactivation of DA. Plasma concentration of DA, N-(N-acetyl-L-methionyl)dopamine(2), DA-SO4, and DOPAC after oral administration of 1 were simultaneously analysed using the compartment model including the first-pass metabolism and two-fraction dissolution process. Good fitting curves were obtained. The apparent formation rate constant of 2(K4) is larger than that of DA-SO4(K5) or DOPAC(K6); thus it was shown that two protective groups of 1 reduced the metabolism of DA and 2 specially played an important role to the reduction of first-pass metabolism. From these results, it was found to be possible to give a pharmacokinetic interpretation for the mechanism of reduction of first-pass metabolism of DA.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1990

In situ perfusion system for oral mucosal absorption in dogs.

To evaluate oral mucosal absorption of drugs in dogs, a newly designed in situ perfusion system with a circulating perfusion chamber was developed. The utility of the perfusion system was investigated by using three drugs: salicylic acid (SA), sulfadimethoxine (SM), and diltiazem (DIL). The oral mucosal absorption of the drugs could be adequately described by first-order rate processes. The absorption rate was independent of the amount of un-ionized drug, which varied with the pH of the solution. The absorption of SA was similar for various oral mucosal sites and for repeated experiments using the same site. Pharmacokinetic analysis for the plasma or medium concentration of SA after perfusion showed that SA was absorbed at the rate constant of 0.071 h-1, and that approximately 70% of SA absorbed from oral mucosa was transferred to the circulating blood.

Absorption↗
PubMed1989

[Changes in hepatic circulation after hepatic arterial embolization--an analysis of factors affecting the development of collaterals].

Forty six patients with follow up angiography after hepatic arterial embolization using gelatin sponge particles were analysed to evaluate the factors affecting development of intra- and extrahepatic collaterals. Significant correlation was demonstrated between the grade of embolization and the development of collaterals (p less than 0.001). Also there was significant correlation between development of collaterals and combined use of anticancer drugs with emboli (p less than 0.001). This suggests the possibility of endothelial damages of the arteries caused by anticancer drugs, which may enhance the permanent arterial occlusion and subsequent development of collaterals. No significant correlation was demonstrated between the numbers of embolization therapy and development of collaterals in this study.

Adult↗
PubMed1989

Pharmacokinetic analysis of single- or multiple-dose plasma drug concentration data with a microcomputer using multi-fraction absorption models.

A Basic program for multi-fraction absorption models was developed to link with another microcomputer program, MULTI, and was named MFA-MULTI. A main frame computer program SIMP, based on a simplex method using differential equations, was also operated using a microcomputer equipped with a FORTRAN compiler and a 8087 floating-point coprocessor. These two programs [MFA-MULTI and SIMP (M)] were applied to the analysis of plasma concentration data of several drugs with irregular absorption profiles. The results by MFA-MULTI and SIMP(M) for the single- or multiple-dose data were almost coincident with those obtained by a SIMP program. The result for nalidixic acid estimated using MFA-MULTI or PKM-MULTI was also compared. The plasma nalidixic acid concentration, with irregular absorption profiles due to characteristics of dissolution in the gastrointestinal tract, was found to be described by a two-fraction absorption model. The MFA-MULTI program was applied to the analysis of plasma cimetidine concentration data with double peaks in humans. Pharmacokinetic absorption behavior of a sustained-release preparation of theophylline after repetitive oral administration was adequately evaluated using MFA-MULTI. In addition, application of multi-fraction absorption models to population pharmacokinetics is discussed.

Administration, Oral↗
PubMed1989

Bioavailability and pharmacokinetics of an oral dopamine prodrug in dogs.

The bioavailability and pharmacokinetics of an oral dopamine prodrug, N-(N-acetyl-L-methionyl)O,O-bis(ethoxycarbonyl)dopamine (1), were examined in dogs, and the mechanism of its absorption and bioactivation was discussed. Compound 1 showed a plasma dopamine concentration that was several times higher than that of dopamine (DA) following oral administration to dogs, while the plasma concentrations of dopamine-30-sulfate (DA-SO4) and 3,4-dihydroxyphenylacetic acid (DOPAC) are lower in comparison with that of DA. The conversion of 1 to DA occurred in proportion to the dose administered. Compound 1 also showed a plasma DA concentration that was several times higher than that of other DA prodrugs reported hitherto. In dog plasma, in vitro, 1 was converted to its deethoxycarbonylated form, N-(N-acetyl-L-methionyl)dopamine (2), while other related compounds, N-(L-methionyl)dopamine (3), N-(L-methionyl)O,O-bis(ethoxycarbonyl)-dopamine (4), and O,O-bis(ethoxycarbonyl)dopamine (5), were rapidly converted to DA (however, 2 was stable in plasma). Bioavailability, based on the AUC of DA, 1, 2, and 5 following oral administration to dogs, increased in the following order: 1, 2, 5, and DA. Thus, it was shown that the two protective groups introduced in 1 served to reduce the first-pass metabolism of the DA moiety in the absorption process. It was also confirmed that 1 is converted to 2 or DA in blood, liver, and intestine.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1989

Pharmacokinetics of an oral sustained-release diltiazem preparation.

The pharmacokinetics of a new oral sustained-release diltiazem preparation (HER-SR, QD) was investigated in dogs and humans. The mean plasma diltiazem concentration in dogs after oral administration of HER-SR showed a prolonged plasma concentration and a double peak. The bioavailability of HER-SR compared with that of a conventional diltiazem preparation (HER) in dogs was approximately 80%, a value that is relatively close to that of humans. The plasma diltiazem concentrations with a double peak in dogs were analyzed using multifraction absorption models. The HER-SR preparation was apparently divided into two fractions (14.3 and 85.7 mg) in the gastrointestinal tract, each fraction was absorbed at rate constants of 4.560 and 0.152 h-1, respectively, and the lag time of the slow-release component was 8.3 h. The plasma diltiazem concentration data in humans after repetitive oral administration of HER-SR were also analyzed using multifraction absorption models. The initial amount of the fast- and slow-release components were 14.8 and 85.2 mg, respectively. The absorption rate constants were 0.730 h-1 for the fast-release component and 0.060 h-1 for the slow-release component. The lag time of absorption for the slow-release component was 6.0 h. The pharmacokinetic parameters were close to those obtained in dogs except for Ka1 and Vd/F. The results confirm that HER-SR had desirable pharmacokinetic characteristics as judged from the simulated plasma diltiazem concentration and the peak-to-trough fluctuation (fluctuation parameters) calculated using the simulated plasma diltiazem concentration. In addition, population pharmacokinetics of HER-SR after repetitive oral administration was examined in humans.

Administration, Oral↗
PubMed1989

New projection for portography.

The right anterior caudocranial oblique (RACCO) view is proposed for improved depiction of the portal venous system. It is achieved by tilting the image intensifier 25 degrees caudal and 25 degrees-30 degrees to the right and maintaining the patient in the supine position. Transarterial portography with digital subtraction angiography was performed in the RACCO and posteroanterior (PA) views in 22 patients. Comparison of the two views revealed that the RACCO view was superior to the PA view of the left main branch in 15 patients (68%) and of the right posterior lobe branch in 19 patients (86%). The RACCO view will be useful for the evaluation of the portal system in patients with primary and secondary hepatic neoplasms in whom detailed images are important for diagnosis treatment planning.

Humans↗
PubMed1989

Response patterns and neuronal networks of photosensory pineal organs.

Pineal organs of poikilotherm animals have photoreceptor cells with cone type structures of disk membranes of the outer segment. In the lamprey, Lampetra japonica, photoreceptors responded to light at 6 X 10(-4) lux as a threshold with hyperpolarization, which modulated the spike discharge of the ganglion cells. Electrophysiological data and high performance liquid chromatography analysis of visual pigments of the pineal suggested the presence of several types of photoreceptor cells. Actually, two different immuno-reactivities were observed in photoreceptors by using antibodies against rod specific protein and cone specific protein. Light information of the environment perceived by the pineal organ is transmitted to the central nervous system and contributes to the control of the locomotor activity rhythm of the lamprey.

Animals↗