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Biomedical subjects

R Fujii

Publications and source records attributed to R Fujii.

At least 199 records · Page 11Linked to original sources
PubMed1986

Action of melanin-concentrating hormone (MCH) on teleost chromatophores.

The in vitro effects of synthetic salmon melanin-concentrating hormone (MCH) on chromatophores of four teleost species were studied. In the erythrophores of the platyfish (Xiphophorus maculatus) and the swordtail (Xiphophorus helleri), and in the xanthophores and amelanotic melanophores of the medaka (Oryzias latipes), pigment aggregation took place in response to MCH even in the absence of Ca2+. In contrast to this, the leucophores of the medaka responded to MCH by the pigment dispersion but only when Ca2+ was present. The motile iridophores of the blue damselfish (Chrysiptera cyanea), which play a predominant role in coloration and its changes, were not affected by the hormone. Pharmacological studies employing various blocking agents suggest that the pigment-aggregating action of MCH is probably mediated through specific receptors possessed by the erythrophores, xanthophores, or amelanotic melanophores, while the pigment-dispersing action on the leucophores might be revealed through the receptors for melanophore-stimulating hormone (MSH).

Animals↗
PubMed1986

Control of chromatophore movements in dermal chromatic units of blue damselfish--II. The motile iridophore.

The mechanism regulating the movements of the unique motile iridophores of the blue damselfish, Chyrsiptera cyanea, was studied. The reaction in which the cells become reflective to light rays of longer wavelength, i.e. from the near u.v. region to the green region, was designated as the "coloring response", while the reverse process was labeled the "clearing response". Both nervous stimuli and adrenergic agonists gave rise to the coloring response, which could be antagonized by alpha adrenolytic agents. The clearing response was accelerated by adenosine and inhibited by theophylline. None of the hormonal substances tested had any effect on the motile response of the cells. It was concluded that the motile iridophores are solely under the control of the sympathetic adrenergic system, and that the co-transmitter, adenosine, may function to antagonize quickly the true transmitter-induced colored state of the cells.

Adenosine↗
PubMed1986

The adsorption of endotoxin molecule in a microporous polyethylene hollow fibre membrane.

The microporous polyethylene hollow fibre membrane is capable of adsorbing small-sized lipopolysaccharides (LPS) prepared by sonication dispersion, column chromatography on Sephadex G-75 and filtration through a filter membrane with a nominal pore size of 0.025 micron. Small-sized LPS had a one-thousandth of endotoxin activity as compared to intact LPS, when determined by the Synthetic Chromogenic Substrate method of LAL with a specific endotoxin activity of 73.7 ng/micrograms LPS. Fluorescent microscopy of fluorescein conjugated LPS on a microporous polyethylene hollow fibre showed that fluorescein-LPS was adsorbed through the entire depth of the membrane texture. Accordingly the adsorption capacity of the filter for small-sized LPS was determined as 1.65 mg LPS/3.68 m2 surface/116 mg fibre/module.

Adsorption↗
PubMed1986

Endotoxin removal from water using microporous polyethylene chopped fibres as a new adsorbent.

A new adsorbent, microporous polyethylene chopped fibre, was produced from a high density polyethylene. This can adsorb lipopolysaccharides (LPS) linearly up to 2 h, and showed the highest capacity to adsorb LPS when compared with two other polyethylene-based adsorbents and a polystyrene-based adsorbent. More than twice as much orange II and 4-nitroquinoline N oxide were adsorbed in the new adsorbent as was LPS. The adsorption isotherm of the new adsorbent for LPS was of Ln type, the correlation between adsorption and concentration of solute was proportional; whereas orange II and 4-nitroquinoline N oxide were of L type (greater adsorption than Ln type); tetrachloroethylene adsorption was of S type, less than Ln type. Adsorption of LPS to the new adsorbent increased when temperature rose, whereas adsorption of orange II and 4-nitroquinoline N oxide decreased. These data suggest that the binding of LPS to the new adsorbent is a hydrophobic interaction, whereas the binding of both orange II and 4-nitroquinoline N oxide is not. The new adsorbent has a greater potential for the removal of endotoxin from tap water than other commercially available adsorbents such as charcoal and Amberlite XAD-2.

Adsorption↗
PubMed1986

Removal of endotoxin from water by microfiltration through a microporous polyethylene hollow-fiber membrane.

The microporous polyethylene hollow-fiber membrane has a unique microfibrile structure throughout its depth and has been found to possess the functions of filtration and adsorption of endotoxin in water. The membrane has a maximum pore diameter of approximately 0.04 micron, a diameter which is within the range of microfiltration. Approximately 10 and 20% of the endotoxin in tap water and subterranean water, respectively, was smaller than 0.025 micron. Endotoxin in these water sources was efficiently removed by the microporous polyethylene hollow-fiber membrane. Escherichia coli O113 culture broth contained 26.4% of endotoxin smaller than 0.025 micron which was also removed. Endotoxin was leaked into the filtrate only when endotoxin samples were successively passed through the membrane. These results indicate that endotoxin smaller than the pore size of the membrane was adsorbed and then leaked into the filtrate because of a reduction in binding sites. Dissociation of 3H-labeled endotoxin from the membrane was performed, resulting in the removal of endotoxin associated with the membrane by alcoholic alkali at 78% efficiency.

Animals↗
PubMed1986

A comparative survey of the type of sympathetic neuro-melanophore transmission in catfishes.

The types of innervation to integumental melanophores were surveyed comparatively within the order Siluriformes. In fish or many families, pigment aggregation within melanophores was found to be under the control of adrenergic sympathetic postganglionic fibers as in other fish. In silurid catfish, on the other hand, the cells were found to be regulated cholinergically, though the fibers concerned were sympathetic postganglionic. Muscarinic cholinoceptors mediate the melanin-aggregating response. In some catfish belonging to Bagridae, Pimelodidae and Callichthyidae, the melanophores strangely possessed cholinoceptors, notwithstanding the fact that they were under adrenergic nervous control. These results were discussed in conjunction with the phylogeny of Siluriformes.

Animals↗
PubMed1986

Adenosine receptors mediate pigment dispersion in leucophores of the medaka, Oryzias latipes.

Using the medaka, Oryzias latipes (orange-red variety), the mechanisms of action on leucophores of adenosine and adenine nucleotides, including cyclic AMP, were studied. All these substances were found to be very effective in dispersing leucosomes. Their pigment-dispersing action was antagonized by methylxanthines. These substances did not aggregate leucosomes. It was concluded that leucophores possess specific binding sites for adenosine, i.e. adenosine receptors, on the cell membrane, which mediate leucosome dispersion. Further, it was shown that even the action of an established intracellular second messenger, cyclic AMP, is primarily manifested through the receptors.

Adenine Nucleotides↗
PubMed1986

Cyclic nucleotide action is mediated through adenosine receptors in damselfish motile iridophores.

Effects of cyclic nucleotides on motile iridophores were examined in the blue damselfish, Chrysiptera cyanea. All of the cyclic nucleotides tested, i.e. cAMP, 2',3'-cAMP and cGMP, accelerated the clearing response of the cells even at concentrations of 10(-5) or 10(-4) M. The action of these nucleotides was effectively antagonized by methylxanthines. These results suggest that the effect of cyclic nucleotides on damselfish iridophores is mediated by adenosine receptors in a similar fashion to the action of adenosine.

Animals↗
PubMed1986

Changes in frontal lobe size with age. A CT study in children.

A series of linear measurements on computed tomography of the brain was performed in 481 children (from newborns up to 5 years of age). Each measurement increased with age in infancy and early childhood. In addition to the commonly used linear measurements, a new index has been devised. This index equals the ratio between the sagittal diameter of the brain and the sagittal midline distance from the anterior border of the brain to a line tangential to the anterior horns. All measurements were made on the scan at the level of the foramen of Monro. This index was called the frontal force index (FFI), because it seemed to reflect the morphologic change in the frontal lobes. The functions related to the frontal lobes, i.e. cognitive functions, develop rapidly during infancy and early childhood. In normally or subnormally developed children the FFI increased during early infancy and decreased in severely retarded children. The FFI is obviously useful in the evaluation of the development of the frontal lobes.

Child, Preschool↗
PubMed1986

The bifrontal fluid collection area and other cerebrospinal fluid spaces at computed tomography in children. Its variations with increasing age and pathologic conditions.

A total of 592 computed tomography examinations of the brain in children were studied from the aspect of age and development. The series was divided into 3 groups with respect to neurologic development: 1) normal without neurologic symptoms, 2) normal or subnormal with neurologic symptoms, and 3) moderately to severely retarded. For evaluation, a method of visual grading was applied for each cerebrospinal fluid space. Concerning the ventricular system, the most significant changes in size with increasing age were noted in the lateral ventricles. There were no significant changes in the third and fourth ventricles. Among the three groups, the enlargement was most prominent in group 3 and less prominent in groups 1 and 2. Concerning the extraventricular spaces, the enlarged bifrontal fluid collection area, the sylvian fissure, the interhemispheric fissure, and the cerebral sulci vanished with increasing age. Similarly to the ventricular system, the enlargement was most prominent in group 3, and less prominent in groups 1 and 2, above the age of 1 year. The relation of these results to age and developmental factors are discussed.

Adolescent↗
PubMed1986

[Clinical evaluation of imipenem/cilastatin sodium in children].

Imipenem/cilastatin sodium (MK-0787/MK-0791) was evaluated for its safety, efficacy and pharmacokinetics in children. Thirty cases of bacterial infections were treated with MK-0787/MK-0791 at a daily dose of 40 to 222 mg/kg for 2.25 to 13 days. Clinical cure rate was 93% and bacteriological efficacy rate was 88%. Treated diseases included severe tonsillitis due to mixed anaerobic infections, pneumonia, sepsis, brain abscess and soft tissue infections. Two cases, one with periosteomyelitis due to methicillin-resistant S. aureus and the other with pulmonary abscess due to Haemophilus influenzae (other than type b), failed to respond to the MK-0787/MK-0791 therapy. The serum half-life of MK-0787 was 0.892 hour in children with normal renal functions. An episode of convulsions in a case of sepsis with bacterial croup and brain edema was considered to be associated with the MK-0787/MK-0791 therapy. From the present study, MK-0787/MK-0791 appears a safe and effective antibiotic when used in children with a variety of bacterial infections.

Bacteria↗