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Biomedical subjects

S Higuchi

Publications and source records attributed to S Higuchi.

At least 523 records · Page 29Linked to original sources
PubMed1983

Interaction of N6-substituted-9-methyladenines to poly-5-bromouridylic acid.

Interaction of N6-methyl-9-methyladenine (m6m9A) to poly-5-bromouridylic acid (poly(BU] was investigated. The stoichiometry of interaction was determined to be 1 m6A:2 BU by equilibrium dialysis. Structural information was obtained from circular dichroism and absorption spectra and a similarity of the structure to the corresponding polymer complex was suggested. Thermodynamic parameters of the interaction was calculated from dependence of TmS on the monomer concentration and compared to those from calorimetric measurements. N6-(delta 2-Isopentenyl) - and N6-allyl-9-methyladenine were also examined of the binding to poly(BU).

Adenine↗
PubMed1982

Quantitative determination of the beta-adrenoceptor stimulant formoterol in urine by gas chromatography mass spectrometry.

A method for the quantitative determination of the beta-stimulant formoterol in urine, using a gas chromatograph--mass spectrometer, is described. Formoterol can be analyzed after the addition of a deuterium-labelled internal standard and conversion to a mixed bis-pentafluoropropionyl-methyl derivative for selected ion monitoring. The detection limit was 5 ng/ml. Urinalysis after the oral administration of formoterol fumarate, using a combined enzymic hydrolysis method, revealed that the drug was conjugated with glucuronic acid in rats, dogs and humans.

Adrenergic beta-Agonists↗
PubMed1982

Cell movements in a living mammalian tissue: long-term observation of individual cells in wounded corneal endothelia of cats.

Although the cells in tissues are known to be motile under special conditions (e.g., during tissue turnover or wound healing), there are not many reports that polygonal cells covering an area without leaving any gaps are also capable of movement. In the present study, cell movements (cell shifting and rearrangement) in a living mammalian eye tissue were documented by identifying and locating individual cells over intervals as long as 100 days. Cat corneal endothelium, a monolayered cell sheet, was wounded by removing a small number (about 180) of endothelial cells from the internal lining of the cornea. Healing of the wounded tissue was observed with a wide-view specular microscope applied to the outer surface of the cornea, enabling us to identify individual cells for as long as two to three months. Cells surrounding the wound underwent areal enlargement, elongated toward the wound, and shifted to cover the wound surface. During days 4-7, cells became rearranged by changing neighbors in such a way that they retained their enlarged size but recovered their non-elongated, original shape. This pattern of cell rearrangement was interpreted by a computer simulation which assumed that cells shorten their boundary length while maintaining contacts with contiguous cells. After day 7, the enlarged cells adjacent to the wounded area gradually contracted and pulled surrounding cells toward the wounded area. These movements were followed by a temporary halt in cell shifting, then by a recovery of shifting and cell elongation. These movements are interpreted as a result of the contractility of endothelial cell microfilaments.

Animals↗
PubMed1982

Vasodilator and hypotensive effects of the optical isomers of nicardipine (YC-93), a new Ca2+-antagonist.

Vasodilator and hypotensive effects of (+) and (-) nicardipine were investigated in anesthetized dogs. When administered intravenously, (+) nicardipine was 3 times as potent as the (-) isomer in increasing vertebral blood flow and in lowering mean blood pressure. When injected into the vertebral artery, (+) nicardipine was also 3 times as potent as the (-) isomer in increasing vertebral blood flow. Upon both routes of administration, the duration of the action after (+) nicardipine was longer than that after the (-) isomer. However, there were no differences of plasma nicardipine levels after intravenous injection of both isomers to conscious beagle dogs. The LD50 values of (+) nicardipine in mice and rats upon intravenous injection were only 1.5-2 times smaller than those of the (-) isomer. These results indicate that there exists a stereoselectivity of vasodilator and hypotensive actions among the nicardipine isomers.

Animals↗
PubMed1982

The effect of cytochalasin B on the superoxide production by alveolar macrophages obtained from normal rabbit lungs.

Resident alveolar macrophages and lung lavage fluids were obtained from normal rabbit lungs. Superoxide production by alveolar macrophages exposed to lung lavage fluids and cytochalasin B was measured by superoxide dismutase-inhibitable nitroblue tetrazolium (NBT) reduction. Glycogen-elicited peritoneal macrophages were used as a control. Cytochalasin B, as well as lung lavage fluids, enhanced superoxide production by resting alveolar macrophages. The cytochalasin B-induced superoxide production was associated with enhanced attachment to glass and with remarkable alterations of the cell surface morphology, probably relating to interference with the microfilament functions of cells. On the other hand, glycogen-elicited peritoneal macrophages showed only a slight production of superoxide when exposed to the same stimulants.

Animals↗
PubMed1981

Specific determination of plasma nicardipine hydrochloride levels by gas chromatography-mass spectrometry.

A highly specific method for the determination of the plasma level of the potent vasodilator 2-(N-benzyl-N-methylamino)ethyl methyl 2,6-dimethyl-4-(m-nitrophenyl)-1,4-dihydropyridine carboxylate hydrochloride (nicardipine hydrochloride) in rats, dogs and humans is described. N-d3-Methyl derivative was added as an internal standard, then the plasma was extracted with diethyl ether and subjected to thin-layer chromatography (TLC) to remove the pyridine analogue, one of the drug's metabolites. The area corresponding to the unchanged drug was identified with simultaneously run N-d7-benzyl derivative under UV light. The unchanged drug with a 1,4-dihydropyridine structure was oxidized with nitrous acid to its pyridine anlogue, which was stable for gas chromatography, and subjected to mass spectrometry at m/e 134 (nicardipine) and m/e 137 (N-d3-methyl derivative). The sensitivity limit was 5 g ml-1. The ratio of the unchanged drug to the value obtained by the method without TLC separation was 100% for rats and 80% for dogs and humans at almost all times investigated after dosing. These results demonstrate that in these species, the amount of pyridine analogue in plasma was very small compared with that of the parent drug.

Animals↗
PubMed1981

Rate of transacylation between 2' and 3'-O-L-phenylalanyladenosine.

The 270-MHz proton NMR spectra of 2'-O-L-phenylalanyladenosine and 3'-O-L-phenylalanyladenosine in deuterated phosphate buffer were analyzed. The transacylation between these two isomers was studied by saturation transfer experiments on H1' proton resonances and the transacylation rate was directly determined to be 0.76 s-1 at pD 6.9 and 25 degrees C. This transacylation rate is appreciably slower than the rate of polypeptide chain elongation, suggesting the presence of enzymatic activity for the transacylation of aminoacyl-tRNA in protein biosynthesis.

Acylation↗
PubMed1981

Persistence of protein, carbohydrate and was components of tubercle bacilli in dermal BCG lesions.

Dermal tuberculous lesions were produced in rabbits with Bacille Calmette Guèrin and biopsied on days 4, 14, 21, 35, and 56. Frozen sections prepared from the biopsy specimens were stained by the peroxidase-antiperoxidase immunocytochemical technique with antisera against whole tubercle bacilli and antisera against the protein B, polysaccharide I, and wax D fractions of tubercle bacilli. In the primary lesions, protein B was often undetectable at 21 days, and polysaccharide I was often undetectable at 35 days. Wax D disappeared more slowly than the other bacillary components evaluated, and some wax D was still found at 56 days (if the lesions had not completely healed). Antisera against intact tubercle bacilli produced results similar to those produced by antiserum against wax D. These studies suggest that the chronicity of tuberculous lesions is due, at least in part, to the persistence of the wax D-like component of tubercle bacilli.

Animals↗
PubMed1981

[Pharmacological study on hydrocortisone 17-butyrate 21-propionate (author's transl)].

The topical and systemic anti-inflammatory activities of hydrocortisone 17-butyrate 21-propionate (HBP) were studied. The systemic anti-inflammatory activities of HBP and reference steroids were examined for their effects on dinitrochlorobenzene dermatitis, carrageenin edema, cotton pellet granuloma and adjuvant arthritis in rats and by the delayed allergic edema test in mice. The topical anti-inflammatory activities of these steroids were examined for their effects on croton oil dermatitis, croton oil ear edema, carrageenin edema and cotton pellet granuloma in rats. Furthermore, effects of these steroids on liver glycogen deposition in mice, thymolysis, and decrease of serum corticosterone level in rats were examined. Systemically administered HBP was less potent than betamethasone 17-valerate (BV), but was almost equal to hydrocortisone 17-butyrate (HB) in anti-inflammatory activity, and its effects on liver glycogen deposition, thymolysis, and the decrease of serum corticosterone level. However, the topical anti-inflammatory activity of HBP was more potent than that of BV and HB, although in the same experiment, thymolytic activity of HBP was less potent than that of BV, but was almost equal to HB. The inhibitory effect of HBP on hypotonic induced hemolysis was weaker than that of BV, but was stronger than that of HB in vitro. The affinity of HBP was higher than that of BV and HB to polymorphonuclear leucocytes used as the inflammatory cells in vitro. On the other hand no marked difference was observed in the affinity to erythrocytes used as the non-inflammatory cells in vitro. These results suggest that HBP is a useful drug which has superior topical anti-inflammatory activity, but has a weak systemic effect.

Animals↗