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Biomedical subjects

K Horiuchi

Publications and source records attributed to K Horiuchi.

At least 253 records · Page 14Linked to original sources
PubMed1982

A reaction cell with short optical path and oxygen electrode compartment for convenient quantitative determination of oxygen binding by hemoglobin.

1. A simple and compact apparatus, with which the oxygen equilibrium of hemoglobin can be determined easily, was constructed and its performance was examined. 2. The oxygen partial pressure and the degree of oxygen saturation in a hemoglobin solution were determined by combined used of a Clark oxygen electrode and a spectrophotometer. 3. This apparatus can be used in a usual 1 cm square cell holder of a commercial spectrophotometer without any modifications, and has the advantage that the light path length of the optical cell is variable and can be shortened to about 2 mm.

Adult↗
PubMed1982

Some characteristics of beta-naphthyl oligophosphates as allosteric effectors of human hemoglobin.

1. Fluorescent organic phosphates. beta-naphthyl oligophosphates, were found to interact with human hemoglobin, and to lower the oxygen affinity. The magnitude of the allosteric effect depended on the number of phosphoric groups in each compound. 2. In analogy with inositol hexaphosphate (IHP). beta-naphthyl tetraphosphate (beta-NapP4) was found to interact with oxyhemoglobin. Therefore, the spectral changes in oxyhemoglobin and carboxyhemoglobin induced by beta-NapP4 and IHP were compared. 3. The extent of spectral changes in oxyhemoglobin induced by beta-NapP4 was smaller than that induced by IHP, whereas the extent of spectral changes in carboxyhemoglobin induced by beta-NapP4 was about twice that by IHP. 4. These results indicate that there is a structural difference between oxyhemoglobin and carboxyhemoglobin.

Allosteric Regulation↗
PubMed1982

Initiation and termination of phage f1 plus-strand synthesis.

The origin of DNA replication of bacteriophage f1 contains a nucleotide sequence that is used both for the initiation of viral (plus) strand synthesis and for its termination. With chimeric plasmids containing two f1 functional origins in the same orientation, synthesis of chimeric plus-strand DNA is initiated, after f1 infection, at either one of the two f1 origins and is terminated at the other. Thus, the chimeric plasmids segregate into two replicons, each of them containing only one f1 origin. This system has been used to test several fragments of the f1 origin varying in size or in nucleotide sequence for their ability to function in either initiation or termination of viral strand synthesis. Our data show that the f1 origin is composed of two overlapping but distinct domains (signals), one for initiation and the other for termination of plus-strand synthesis.

Base Sequence↗
PubMed1982

Deferoxamine, a promising bifunctional chelating agent for labeling proteins with gallium: Ga-67 DF-HSA: concise communication.

A new efficient method has been developed for the labeling of various biologically important proteins with radiogallium, using deferoxamine (DF) as a bifunctional chelating agent. Human serum albumin (HSA) was chosen for studying the DF coupling reaction by a glutaraldehyde two-step method. The DF-HSA conjugate obtained was then easily labeled with Ga-67 with high efficiency and reproducibility. High stability of the Ga-67 DF-HSA was observed both in vitro and in vivo. In rats the half-time of blood clearance at the first phase was 234 min for the Ga-67 DF-HSA, whereas most conventional I-131 HSA gives 121 min. The excellent pharmacological and physiological properties were assessed by plasma clearance and plasma volume measurements in normal volunteers. Even at 2 hr after injection, (90.0 +/- 3.0)% of Ga-67 DF-HSA was retained within the vascular space. The mean plasma volume per kilogram of body weight, measured with Ga-67 DF-HSA, was 46.6 +/- 3.4 ml/kg, compared with 52.2 +/- 2.4 ml/kg as determined with I-131 HSA in the same men.

Animals↗
PubMed1981

Analysis of 99mTc-pyridoxylidene-glutamate complex formation and its preparation with tin-adsorbed-resin: Sn-Resin kit method.

99mTc-Pyridoxylidene-glutamate (Tc-PG) was introduced in 1975 by Baker et al. as a cholescintigraphic agent. Nevertheless its routine use has been limited due to the autoclaving process involved. To shorten the labeling procedure, an analysis of Tc-PG complex formation using the stannous chloride method was carried out. Sn-Resin (stannous ion adsorbed onto cation exchange resin) was used for labeling a stable Tc-PG with high efficiency. A preautoclaved complex of pyridoxal and glutamate was required but the labeling procedure took only 10-15 min after the elution of 99m-TcO4- from the generator. Formation of a complex other than a 99mTc-complex of the Schiff -base ligand pyridoxylidene-glutamate is discussed. The new formulation of a Tc-PG kit (Sn-Resin) simplified the labeling method and reproducible data to that already reported by Baker was obtained in chromatographic studies. Its suitability in hospital departments has already been shown in clinical studies.

Bile↗
PubMed1981

Technetium coordination state as a factor of stability in 99mTc-complexes used in hepatobiliary system: comparative studies on 99mTc-complexes of pyridoxal with glutamate (Tc-PG) and isoleucine (Tc-PI).

Studies on 99mTc-Penicillamine (Tc-Pen) have given us some insight into the significance of the technetium coordination state in hepatobiliary clearance behavior. A 99mTc-complex of pyridoxal and glutamate (Tc-PG) prepared by Baker et al. (1975) using an autoclaving process or by a Sn-Resin kit method (Horiuchi 1981) was compared with a 99mTc-complex of pyridoxal and isoleucine (Tc-PI) prepared by the method of Kato and Hazue (1978) through an intermediate compound of stannous ion, at room temperature. Tc-PG and TcPI complexes analyzed by thin layer chromatography, sephadex column chromatography (G-15), octanol extraction, and ligand exchange reaction showed different chemical properties. Their biological evaluation also demonstrated great differences in biodistribution in mice, metabolic studies, protein binding, and rat bile excretion. Tc-PG was estimated as an hepatobiliary agent with strong metal-ligand binding, inert to ligand exchange reaction with Pen at physiological pH; the likely occurrence of technetium in a mononuclear or dinuclear state providing the great stability observed in its biological and in vivo behavior was compared with the relatively weaker binding observed in Tc-PI, a highly lipophilic complex of high liver partition but of low stability, denoting its different chemical characteristics. The technetium coordination state in radiopharmaceuticals is responsible for the integrity of the molecule while in the blood pool and its relevance in impaired liver uptake is discussed.

Animals↗
PubMed1981

Rise time of pure-tone stimuli in brain stem response audiometry.

In order to identify the area of a pure tone stimulus effective for evoking the auditory brain stem response (ABR), the amplitude, latency and detectability of the response were measured as a function of stimulus rise time with a fixed onset slope of a linear-shaped envelope. The test was performed on 8 normal adults with 2- and 0.5 -kHz tone pips at various intensity levels from 50 to 15 dB HL. The ABR was elicited by the very early part of the stimulus, and the succeeding part had little effect in eliciting the response, if the initial part was intense enough to evoke the response. At lower intensity levels, where the initial part did not reach an intensity level sufficient to evoke a full size response, a limited period of the succeeding part participated in evoking the response. The effective duration of the stimulus was estimated at 1.5 ms for 2 kHz and at 3 ms for 0.5 kHz. From these results, the authors propose that acceptable rise times of pure-tone stimuli for brain stem response audiometry are 3, 2, 1.5 and 1 ms for tone pips of 0.5, 1, 2 and 4 kHz, respectively.

Acoustic Stimulation↗
PubMed1981

Increased histone acetylation and deacetylation in rat ascites hepatoma cells.

Rates of histone acetylation and deacetylation in nuclei from fetal, adult, and two kinds of neoplastic rat hepatocytes were examined. Histone acetylation in isolated nuclei was measured in the presence of 6 mM sodium n-butyrate, a potent inhibitor of deacetylase, and in the absence of the inhibitor. The deacetylase activity was estimated from the difference between the rates with or without the inhibitor. Both histone acetylation and deacetylation in nuclei from hepatoma cells (AH 66 cells) occurred two times faster than those of nuclei from fetal and adult livers regardless of alpha-fetoprotein production. This increased acetylation and deacetylation in hepatoma cells may be ascribed to either the increased activities of the enzymes or the increased accessibility of histone to the enzymes in the chromatin. Autoradiographic analysis of acetylated histones showed that all of the internal histones of the nucleosomes were acetylated and that apparent difference was found in the pattern of acetylated fractions between hepatoma nuclei and normal liver cell nuclei.

Acetylation↗