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Biomedical subjects

A Yagi

Publications and source records attributed to A Yagi.

At least 73 records · Page 4Linked to original sources
PubMed1994

Effects of tanshinone VI derivatives on post-hypoxic contractile dysfunction of perfused rat hearts.

The present study was undertaken to elucidate the effects of sodium tanshinone VI 1-phenolate (1), 1'-O-hydrogen succinyltanshinone VI 1-O-hydrogen succinate (2), and disodium 1'-O-succinyltanshinone VI 1-O-succinate (3), water-soluble derivatives of tanshinone VI, on post-hypoxic contractile recovery of isolated perfused rat hearts. The effects were compared with those of tanshinone VI as tested previously. The hearts were perfused for 20 min under hypoxic conditions, followed by 45 min reoxygenation, and their cardiac performance was determined. Changes in tissue sodium, potassium, calcium, and magnesium contents after reoxygenation, and release of creatine kinase and purines and bases (ATP metabolites) during hypoxia/reoxygenation were also examined. The derivatives were dissolved in a Krebs-Henseleit buffer and administered at concentrations of 42 nM into the buffer. Hypoxia/reoxygenation resulted in slight recovery of cardiac contractile force, significant alterations in tissue ion concentrations, and pronounced release of creatine kinase and ATP metabolites, suggesting hypoxia/reoxygenation-induced functional and morphological damage. The tanshinone VI derivatives improved post-hypoxic contractile recovery, which was associated with restoration of tissue ionic concentrations, and diminishment of the release of creatine kinase and ATP metabolites from the hypoxic/reoxygenated hearts. The efficacy of these compounds was similar to that of tanshinone VI. The results suggest that water-soluble tanshinone VI derivatives, like tanshinone VI itself, are beneficial for hypoxia/reoxygenation injury.

Adenosine Triphosphate↗
PubMed1994

Exaggerated vascular response due to endothelial dysfunction and role of the renin-angiotensin system at early stage of renal hypertension in rats.

We investigated whether endothelial dysfunction might contribute to the exaggerated vasoconstriction that was induced by the administration of norepinephrine at the early stage of one-kidney, one-clip renal hypertension (1K1C) in rats. We also studied the role of the renin-angiotension system in this phenomenon. Male Wistar rats were killed 48 hours after the induction of renal artery stenosis or sham operation, and ring preparations of the thoracic aorta were obtained. The isometric contraction and relaxation of aortic strips produced by norepinephrine and acetylcholine, respectively, were recorded with a force-displacement transducer. The aorta of 1K1C rats showed a significantly (P < .05) exaggerated contractile response to norepinephrine as compared with that of control rats. Rubbing the endothelium and treatment with methylene blue or NG-monomethyl L-arginine acetate augmented the contractile responses to norepinephrine to a greater extent in control rats than in 1K1C rats; therefore, the responses of the groups did not differ significantly. In the second experiment, rats received 0.05% captopril, 0.02% enalapril, or 0.02% nicardipine in the drinking water for 1 day before and for 48 hours after the induction of renal artery stenosis or sham operation. The increased contractile responses of the aorta to norepinephrine in 1K1C rats were normalized to the level of the control rats by treatment with either captopril or enalapril but not with nicardipine. These results suggest that the endothelial dysfunction may contribute to the exaggerated norepinephrine-induced vasoconstriction observed in the 1K1C rats and that angiotensin I-converting enzyme inhibitors can restore the endothelial function.

Acetylcholine↗
PubMed1994

Relationship between lipophilicity and skin permeability of various drugs from an ethanol/water/lauric acid system.

The in vitro skin permeability of 16 drugs with a wide range of lipophilicity (log P; -0.95-4.40) was evaluated by the use of an ethanol/water (60/40) binary vehicle with or without lauric acid as a permeation enhancer. The enhancing effect by the addition of lauric acid to the ethanol/water (60/40) binary vehicle could be observed from the aspect of both permeation rate and lag time. The permeation rate increased with an increase in the hydrophilicity of the drugs. It was considered that lauric acid exerts an effect on both the polar and nonpolar regions of lipids of the stratum corneum, and the cooperative interaction of ethanol and lauric acid increases the participation of the polar pathway of drugs. The relationship between lipophilicity and skin permeability of the drugs from the ethanol/water (60/40) binary vehicle with lauric acid showed a parabolic shape, with its peak at a more hydrophilic range (log P; 0.19) compared with other past references (log P; 2-3). The ethanol/water (60/40) binary vehicle with lauric acid appears to be a good candidate as a vehicle for transdermal therapeutic systems for hydrophilic drugs.

1-Octanol↗
PubMed1994

Protective effect of ginseng saponins against impaired brain growth in neonatal rats exposed to ethanol.

This study was performed to determine the active constituents of the root of Panax ginseng C. A. Mayer in the amelioration of ethanol-induced impediment of brain growth in the neonatal stage. To establish an animal model of the brain growth impediment caused by ethanol, ethanol (6 g/kg s.c.) was administered to rat pups on postnatal day 6, which corresponded to the third trimester of pregnancy for humans. Brain weight, especially cerebellar weight, was significantly reduced in the ethanol-exposed pups. In contrast, neither separation from dams nor pentobarbital treatment affected brain weight. A saponin fraction of ginseng extract prevented this ethanol-induced reduction of brain weight. Some ginseng saponins including ginsenosides Rg1, Rb2, Rd, Rf and Re effected stimulated a potent recovery of cerebellum growth in this animal model.

Animals↗
PubMed1994

A new device for indirect blood pressure measurement in rabbits.

We evaluated the reliability of a new device for indirect measurement of systolic blood pressure in normal and hypertensive New Zealand White rabbits. This device consisted of an ear unit composed of an air chamber and sensitive photoelectric sensors, and was connected to an apparatus used for the tail-cuff method. Systolic blood pressure was determined by simultaneous recordings of pulse volume oscillations of the central ear artery and the chamber pressure. The blood pressure in 8 normal rabbits was 116 +/- 7/78 +/- 6 mmHg (mean +/- SEM) by direct measurement and 100 +/- 6 mmHg by indirect measurement. In a one-kidney, one-clip hypertensive model, the new device showed that blood pressure increased from 100 +/- 7 to 158 +/- 7 mmHg over 4 weeks. After nicardipine was injected, blood pressure fell from 191 +/- 10/114 +/- 10 to 117 +/- 7/72 +/- 8 mmHg as measured by the direct method, and from 158 +/- 7 to 92 +/- 6 mmHg as measured by the new device. A strong correlation (r = 0.91, p < 0.01) was observed between direct and indirect measurements. Our findings indicate that this device provides rapid, easy and reliable measurement of blood pressure in rabbits.

Animals↗
PubMed1994

(S)-linalyl, 2-phenylethyl, and benzyl disaccharide glycosides isolated as aroma precursors from oolong tea leaves.

Three glycosides, 6-O-beta-D-xylopyranosyl-beta-D-glucopyranosides (beta-primeverosides) of the aroma constituents, linalool, 2-phenylethanol, and benzyl alcohol, were isolated as aroma precursors from the tea leaves (Camellia sinensis var. sinensis cv. Shuixian and Maoxie, cultivars for oolong tea). The isolation was guided by acid or enzymatic hydrolysis, and subsequent GC and GC-MS analyses. The linalyl glycoside is the first example of naturally occurring (S)-linalyl beta-primeveroside.

Benzyl Alcohols↗
PubMed1994

trans- and cis-linalool 3,6-oxide 6-O-beta-D-xylopyranosyl-beta-D-glucopyranosides isolated as aroma precursors from leaves for oolong tea.

New glycosidic aroma precursors (1 and 2) of the main volatile constituents, trans- and cis-linalool 3,6-oxides (linalool oxides I and II), were isolated from oolong tea leaves (Camellia sinensis var. sinensis cv. Maoxie). The isolation was guided by an enzymatic hydrolysis with acetone powder prepared from fresh tea leaves (cv. Yabukita) followed by GC or GC-MS analyses. Chromatographic purification of hot water extracts of the tea leaves on active charcoal, Amberlite XAD-2, and Sephadex LH-20 columns as well as HPLC gave two new glycosides, trans- and cis-linalool 3,6-oxide 6-O-beta-D-xylopyranosyl-beta-D-glucopyranosides (1 and 2).

Acyclic Monoterpenes↗
PubMed1994

Aldosterone response to adrenocorticotrophin and furosemide in primary aldosteronism after prolonged spironolactone treatment.

We evaluated the effects of prolonged spironolactone treatment on aldosterone secretion in patients with primary aldosteronism. The patients were hospitalized and underwent a furosemide test with or without dexamethasone, as well as an adrenocorticotrophin (ACTH) test. In untreated patients, neither plasma renin activity (PRA) nor plasma aldosterone showed a response in the furosemide test. In patients receiving spironolactone, furosemide increased significantly both the PRA and the plasma aldosterone concentration (from 2.6 +/- 0.8 to 7.0 +/- 2.0 micrograms.l-1.h-1 (p < 0.05) and from 345.6 +/- 55.8 to 492.7 +/- 76.8 ng/l (p < 0.05), mean +/- SEM, respectively). Dexamethasone administration had no effect on the results of the furosemide test (p > 0.1). However, dexamethasone tended to decrease the basal plasma aldosterone concentration in the untreated patients, but not in the patients receiving spironolactone. In the ACTH test, the plasma aldosterone concentration increased significantly in the untreated patients (from 549.0 +/- 69.8 to 1169.3 +/- 165.5 ng/l, p < 0.01), but there was no significant aldosterone response in the spironolactone-treated patients (from 885.5 +/- 204.9 to 1260.3 +/- 289.2 ng/l, p > 0.1). We conclude that aldosterone secretion is mainly dependent on ACTH in the untreated patients with primary aldosteronism and is more strongly regulated by the renin-angiotensin system during spironolactone treatment.

Adrenocorticotropic Hormone↗
PubMed1993

Effect of hydrophilic and lipophilic vehicles on skin permeation of tegafur, alclofenac and ibuprofen with or without permeation enhancers.

The effects of an ethanol/panasate 800 (tricaprylin) (40/60) system as a lipophilic vehicle, and an ethanol/water (60/40) system as a hydrophilic vehicle, with or without permeation enhancers for in vitro skin permeation and in vivo skin absorption of tegafur, alclofenac and ibuprofen with different lipophilicity, were evaluated. The in vitro and in vivo skin permeability of tegafur, alclofenac and ibuprofen was enhanced by the use of ethanol/panasate 800 (40/60) or ethanol/water (60/40) binary vehicles as a donor composition. However, the two vehicles showed contrastive properties in relation to the extent of permeation enhancement of the three drugs: tegafur > alclofenac > ibuprofen for the ethanol/panasate 800 (40/60) system, and ibuprofen > or = alclofenac > tegafur for the ethanol/water (60/40) system. When lauric acid, as a permeation enhancer, was added to both of the binary vehicles, the in vitro and in vivo skin permeability of three drugs further increased, and the in vivo absorption rate of the drugs from the ethanol/water (60/40) system was larger than that from the ethanol/panasate 800 (40/60) system. In conclusion, it was suggested that the ethanol/panasate 800 (40/60) lipophilic binary vehicle is useful for hydrophilic drugs, and conversely, the skin absorption of lipophilic drugs can be improved by the use of the ethanol/water (60/40) hydrophilic binary vehicle with or without lauric acid as a permeation enhancer.

Animals↗
PubMed1993

Hepatic copper accumulation in patients with primary biliary cirrhosis.

Liver biopsy specimens from 18 patients with primary biliary cirrhosis were examined histochemically and by energy-dispersive x-ray microanalysis. Using two indices, we classified hepatic copper accumulation into three stages based on the Cu x-ray intensity of cuproproteins that had accumulated in hepatocyte lysosomes and on the binding ratio of postulated copper transfer proteins between the cytosol and lysosomes. Eight patients were in stage 1 with an initial accumulation of lysosomal cuproproteins, mediated by transfer proteins not saturated with copper. Two patients were in stage 2, in which transfer proteins were saturated with copper. The first two stages gave negative results for histochemical copper. The remaining eight patients were in stage 3, in which copper accumulation detected by histochemical included transfer proteins saturated with copper and large amounts of lysosomal cuproproteins. Five patients (one each in stages 1 and 2, and three in stage 3) underwent a second liver biopsy after treatment with 600 mg of ursodeoxycholic acid daily for 14 to 39 months. Results of blood chemistry tests improved, but liver histologic findings and copper accumulation were unchanged in all five patients. It seems likely that ursodeoxycholic acid does not affect the copper accumulation in hepatocyte lysosomes that reflects the state of cholestasis in patients with primary biliary cirrhosis.

Adult↗
PubMed1993

Cuproproteins of hepatocyte lysosomes in normal and fatty liver.

The pathophysiological significance of cuproproteins in hepatocyte lysosomes was studied in 7 patients with structurally normal livers and 13 patients with fatty livers by energy-dispersion X-ray microanalysis. In most patients, in both groups, copper and sulfur coexisted in hepatocyte lysosomes. The correlation between copper and sulfur indicated that copper transfer between the cytosol and lysosomes was mediated by a cuproprotein. The copper indices of the lysosomal proteins and transfer proteins were high in some fatty livers. These observations suggest that cuproproteins in hepatocytes are not necessarily pathological, but are present in greater amounts in some fatty livers, probably because of impaired bile drainage.

Adult↗
PubMed1992

Localization of actin, alpha-actinin, and tropomyosin in bovine spermatozoa and epididymal epithelium.

Actin, alpha-actinin, and tropomyosin were localized in the testicular, epididymal, and ejaculated spermatozoa and in the epithelium of the bovine epididymis by means of specific antibodies using an indirect immunofluorescence technique. Immunocytochemical results were confirmed by the western blot analysis. Independent of the method of fixation, washing, or sonication, actin, alpha-actinin, and tropomyosin were all consistently localized in the neck of the spermatozoa. Actin and tropomyosin present in the postacrosomal area could be removed by sonication, whereas alpha-actinin in the basal plate appeared to be resistant to the treatment. In the unwashed spermatozoa alpha-actinin-specific immunofluorescence was seen over the acrosomal area, whereas in the washed sperm it appeared as a narrow cap at the margin of the head. In the latter location, its distribution was similar to that of tropomyosin. In the majority of preparations, tropomyosin could be localized in the principal piece of the tail. Even though some actin-specific immunofluorescence could be identified in the principal piece of the tail of the testicular and epididymal spermatozoa, a strong immunoreaction appeared only in the ejaculated spermatozoa. In the principal cells of the epididymal epithelium, specific fluorescence for actin, alpha-actinin, and tropomyosin occurred in the apical junctional complex. Basal bodies of the solitary cilia of the epididymal epithelium were labelled with antitropomyosin and anti-alpha-actinin antibodies. Besides offering new information about the cytoskeletal composition of the mammalian sperm, the present results support the hypothesized homology between the connecting piece of the sperm neck and the basal body of the cilia.

Actinin↗
PubMed1992

Negative brain potentials elicited by an unexpected color patch or word.

The purpose of this study was to examine whether a physical stimulus that deviates from a semantic context can elicit the N400 component of event-related brain potentials (ERPs). ERPs were recorded while 12 students judged the veracity of a simple statement (e.g., red/is not/blue) presented with the order of subject (S), object (O), and verb (V), which is normal in Japanese grammar. In one condition, S was a color patch and O was a word representing the color, while in the other condition, S was a color name and O was a patch. In both conditions, a late additional negative potential was elicited by the O stimulus when it was mismatched with S. In addition, the negativities elicited by the incongruous color patch and word had the same morphology and scalp distribution. The results indicate that not only a word but a physical stimulus which deviates from a semantic context can elicit the N400 component.

Adult↗
PubMed1992

Role of norepinephrine in the lack of reflex tachycardia after angiotensin converting enzyme inhibitor treatment.

Angiotensin converting enzyme inhibitors decrease blood pressure without causing reflex tachycardia in hypertensives, but do not always do so in normotensives. To investigate this phenomenon, hemodynamic changes in normotensive rabbits receiving a subpressor dose of norepinephrine were studied following captopril or diltiazem treatment. We also investigated the effect of captopril on baroreceptor reflex in relation to norepinephrine infusion; the baroreflex sensitivity was determined by the relationship between mean arterial pressure and pulse interval receiving graded doses of phenylephrine. Captopril infusion decreased mean arterial pressure and pulse interval from 84 +/- 4 to 74 +/- 5 mmHg and 244 +/- 7.4 to 216 +/- 7.6 msec, respectively. In contrast, in rabbits receiving a norepinephrine infusion captopril lowered mean arterial pressure to the same extent (92 +/- 5 to 76 +/- 3 mmHg, p less than 0.05) without producing reflex tachycardia. When diltiazem was administered, reflex tachycardia occurred in rabbits both with and without a norepinephrine infusion. There was no difference in the baroreflex sensitivity between rabbits receiving norepinephrine with and without captopril treatment. However, the baroreflex curve showed a slight shift to lower pressures after norepinephrine infusion in the rabbits receiving captopril. These results suggest that elevating circulating norepinephrine might be involved in preventing reflex tachycardia after captopril.

Animals↗
PubMed1992

Three stages of copper accumulation in hepatocellular lysosomes: X-ray microanalysis of copper-loaded golden hamsters.

Male golden hamsters were loaded with copper by supplying them for up to 12 weeks with drinking water containing 0.5% cupric acetate. The copper feeding increased hepatic copper to widely varying levels. Energy dispersive X-ray microanalysis could always identify a copper-sulphur complex in the hepatocyte lysosomes of copper-loaded hamsters and the X-ray intensity of copper was found to be a reliable parameter to measure in-situ copper accumulation. Combining this parameter with the copper binding ratio expressed by delta Cu/delta S enabled us to discern two stages of sub-histochemical copper accumulation. The first stage was marked by low levels of both lysosomal copper and binding ratio, which suggested that this initial copper transfer was mediated by unsaturated cuproproteins. The second stage was characterized by median amounts of lysosomal copper and a binding ratio of more than 0.50. At the third stage, histochemically detectable copper appeared in animals whose lysosomal copper was extraordinarily high in later experimental periods. With the copper binding ratio being in the same range of 0.50-0.83, it seemed that saturated cuproproteins were the main mediator of copper transport in the later two stages.

Animals↗
PubMed1991

Effect of bright light in the morning on diurnal variations of pineal indoles in NZBWF1 mice.

Exposure to bright light (2000 lx) for 2 h at the beginning of a 12 h light period (10 lx) resulted in about 1 h advances in the onset and termination of N-acetylserotonin (NAc5HT) synthesis in the pineal gland of NZBWF1 strain mice compared with those in mice not exposed to bright light. These effects are in contrast with the effect of exposure to bright light throughout the light period, which delayed the onset of pineal NAc5HT synthesis in NZB mice. The possible relationship of these effects with the mechanism of action of phototherapy of human affective disorder is discussed.

Animals↗