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H Harashima

Publications and source records attributed to H Harashima.

80 records · Page 5Linked to original sources
PubMed1984

Comparison between in-vivo and in-vitro tissue-to-plasma unbound concentration ratios (Kp,f) of quinidine in rats.

The comparison between in-vivo and in-vitro tissue-to-plasma concentration ratio of drug unbound (Kp,f) has been made using quinidine as a model for weak basic drugs. In-vitro Kp,f-values were calculated from the binding data to tissue homogenates determined by equilibrium dialysis. In-vivo Kp,f-values were calculated from the tissue distribution data after intravenous administration of quinidine, by considering the difference in the unbound concentration between plasma and the tissues produced by the pH difference across the cell membrane. It was concluded that the extensive tissue distribution of quinidine observed in-vivo may be explained by tissue binding and the pH-difference across the cell membrane in most tissues.

Animals↗
PubMedDate not supplied

No effect of age on the dose requirement of thiopental in the rat.

With increasing human age (20-80 years), the electroencephalogram (EEG) dose requirement for the intravenous anesthetic thiopental decreases approximately 10% per decade of life. The goal of this study was to compare the dose required to attain isoelectric EEG in young (4-5 month) vs. aged (24-25-month) Fischer 344 rats. One second isoelectricity was found to be an endpoint where minimal cardiorespiratory depression occurred. The effects of age, infusion rate, and repeated administration were examined in nine young and nine old rodents. Thiopental dose requirement increased with increasing infusion rates. Repeated administration at two-day intervals did not demonstrate tolerance to thiopental. No difference in thiopental dose requirement was detected in the young vs. elderly rats. In a separate group of five young and five old rats, thiopental plasma, brain, heart, and CSF concentrations were measured when five seconds of EEG isoelectricity was achieved: no consistent differences were noted. The rat may not be an appropriate model to investigate acute age-related anesthetic effects in humans, because cardiovascular changes with age are dissimilar between species.

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PubMedDate not supplied

Stearylated arginine-rich peptides: a new class of transfection systems.

Membrane-permeable arginine-rich peptides, such as HIV-1 Tat-(48-60), HIV-1 Rev-(34-50), and flock house virus (FHV) coat-(35-49), have been shown to possess the ability to transfect COS-7 cells with luciferase-coding plasmid as efficiently as polyarginine (MW 5000-15 000) and polylysine (MW 9800). Not only these virus-derived cationic peptides but also oligoarginines of 4-16 residues were found to be able to transfect cells. In the case of the Tat, FHV, and octaarginine peptides, N-terminal stearylation of the peptides increases the transfection efficiency by approximately 100 times to reach the same order of magnitude as that of LipofectAMINE, one of the most efficient commercially available transfection agents. Also, a certain correlation was observed between the transfection efficiency of stearyl-(Arg)n peptides (stearyl-Rn: n = 4, 8, 12, 16) and the membrane permeability of the corresponding (Arg)n peptides (Rn).

Amino Acid Sequence↗
PubMedDate not supplied

Nonlinear tissue distribution of ouabain in rabbits.

Nonlinear and slow tissue distribution of ouabain was found in rabbits, and the contribution of the ouabain binding to Na+,K+-ATPase was also examined in the heart. The tissue-to-plasma concentration ratio (Kp) of ouabain in each tissue increased with time until 120 min. In addition, the Kp also depended on the plasma concentration (Cp). In the heart, Kp decreased from 12.6 +/- 1.2 to 1.9 +/- 0.2 with the increase of the Cp from 67.3 +/- 5.0 to 497 +/- d 85.2 nM. These data indicate that ouabain distributes slowly into each tissue by a saturable process. The specific binding of ouabain to cardiac Na+,K+-ATPase was measured using crude homogenates. The dissociation constant and the binding capacity were 86 nM and 2.3 nmol/ml of 0.5% homogenate, respectively. The tissue-to-plasma concentration ratio (Kp,vitro) was constructed based on these binding parameters and this explained almost 40% of the Kp obtained in vivo. These results suggest that the ouabain binding to Na+,K+-ATPase might play one of the major roles in the slow and nonlinear tissue distribution of ouabain in rabbits.

Animals↗
PubMedDate not supplied

Clinical indication of digital subtraction angiography.

Intravenous subtraction angiography with Technicare DR 960 has been performed in the Department of Diagnostic Radiology and Nuclear Medicine, National Medical Center Hospital. All procedures are based on the non-invasive technique, i.e. with 5 cm length and 19 G. of cannula to the ante-cubital vein, and small amount of contrast material of half ml per kg of body weight kg as maximum dosage for pediatric patients. Image quality was evaluated by visual classification such as excellent, good, fair and poor. Among 335 procedures, 303 cases have brought useful diagnostic informations. 156 cases were excellent and good (47%). There were several specialized informations which might be worthwhile for DSA evaluation, i.e. 1. overlapping images, 2. static dynamic images, 3. density controlled image analysis, 4. three vessel visualized images and 5. well demarcated tumor images of extremities. Since the halo image around the true lumen of aneurysma suggested the outline of the false lumen, this phenomena might indicate the aneurysmal wall thickness. Poor risk patients and outpatients have been selected as our DSA candidates. The patient who is indicated for catheter technique angiogram were not examined by DSA.

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