Biomedical subjects

Y Fujimoto

Publications and source records attributed to Y Fujimoto.

At least 109 records · Page 6Linked to original sources

PubMed2000

Nicorandil attenuates both temporal and spatial repolarization alternans.

T-wave alternans (TWA) on the electrocardiogram have been frequently associated with long QT syndrome (LQTS) and abrupt rate change. The present study investigated the effect of the potassium channel opener nicorandil on the repolarization alternans at the endocardium and the epicardium in the left ventricle. Electrocardiogram and transmural monophasic action potentials from the endocardium and the epicardium were simultaneously recorded in Langendorff-perfused guinea pig hearts. The hearts were paced at a basic cycle length (BCL) of 240 ms and the cycle length (CL) was abruptly shortened to 170 ms to induce repolarization alternans. Disopyramide and nicorandil were used to increase or attenuate repolarization alternans, respectively. Repolarization alternans were numerically expressed as the sum of the absolute difference between consecutive monophasic action potential durations at 90% repolarization (MAPD90) in the first 10 beats. In the control hearts, the MAPD90 alternans were 78.6 +/- 14.9 ms at the endocardium, and 49.8 +/- 58 ms at the epicardium (P = .03 endocardium vs epicardium). Disopyramide (2 microg/mL) increased the MAPD90 alternans to 186.6 +/- 30.6 ms at the endocardium and 116.4 +/- 16.5 ms at the epicardium, and enhanced the difference of repolarization alternans between the endocardium and the epicardium (transmural dispersion) from 28.8 +/- 11.3 ms to 70.2 +/- 18.7 ms (P = .02 vs controls). Nicorandil (400 ng/mL) suppressed the MAPD90 alternans to 79.6 +/- 16.3 ms at the endocardium and 56.0 +/- 11.8 ms at the epicardium, and attenuated the transmural dispersion to 23.6 +/- 6.0 ms (P = .02 vs disopyramide-administrated hearts). Our results suggest that nicorandil attenuates both temporal (beat-to-beat) and spatial (between the endocardium and the epicardium) repolarization alternans induced by the combination of cycle length changes and disopyramide administration.

Animals↗

PubMed2000

Three new triterpenoid saponins from the seeds of Vaccaria segetalis.

Three new triterpenoid saponins, named segetoside G(1), H(2) and I(3), have been isolated from the seeds of Vaccaria segetalis. On the basis of chemical reaction and spectral data, their structures have been established as: 28-O-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-[alpha-L-arabinofuranosyl (1-->3)]-beta-D-(4-O-acetyl)-fucopyranosyl-gypsogenin-3-O-beta-D-galactopyranosyl-(1-->2)-beta-D-(6-O-butyl ester)-glucuronopyranoside (1), 28-O-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-[alpha-L-(5-O-acetyl)-arabinofuranosyl-(1-->3)]-beta-D-(4-O-acetyl)-fucopyranosyl-gypsogenin-3-O-beta-D-galactopyranosyl-(1-->2)-beta-D-glucuronopyranoside (2) and 28-O-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-[alpha-L-(5-O-acetyl)-arabinofuranosyl-(1-->3)]-beta-D-(4-O-acetyl)-fucopyranosyl-quillaic acid-3-O-beta-D-galactopyranosyl-(1-->2)-beta-D-glucuronopyranoside (3).

China↗

PubMed2000

Mulberry leaf extract inhibits the oxidative modification of rabbit and human low density lipoprotein.

In a previous study, we demonstrated that the intake of mulberry leaves or their 1-butanol extract (MLBE) reduced the concentration of serum lipids and atheromatous thickening of arterial intima in hypercholesterolemic rabbits. In the present study, we investigated the antioxidative activity of MLBE and isoquercitrin, the main component of MLBE. First, we determined the effect on a stable radical agent, finding that quercetin, isoquercitrin and MLBE scavenged the DPPH radical. We then determined the copper-induced oxidative modification of rabbit and human low-density lipoprotein (LDL). Oxidation of LDL was spectrophotometrically monitored by changes in absorbance at 234 nm accompanied by the formation of conjugated dienes, and measured the formation of thiobarbituric acid reacting substances (TBARS). Quercetin, an aglycone of isoquercitrin, inhibited the formation of conjugated dienes and TBARS by copper-induced oxidative modification of rabbit and human LDLs. MLBE and isoquercitrin also inhibited the oxidation of LDL. These results indicate that mulberry leaves inhibit the oxidative modification of LDL and suggest that mulberry leaves may had prevent atherosclerosis.

Animals↗

PubMed2000

Magnetic resonance lymphography of profundus lymph nodes with liposomal gadolinium-diethylenetriamine pentaacetic acid.

Lymphography, especially imaging of profundus lymph nodes, is a useful tool for diagnosis of cancer metastases in lymph nodes. However, positive enhancement agents for magnetic resonance lymphography (MRL) have not been available, since the positive imaging agents so far introduced are low-molecular-weight materials that are not trapped in lymph nodes. For the purpose of improved positive enhanced MRL, we employed liposomes as carriers of a positive enhancer, gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA). Magnetic resonance (MR) imaging was performed after subcutaneous injection of Gd-liposomes into the hind feet of rabbits which had reactive enlarged retroperitoneal lymph nodes. As a result, not only popliteal but also profundus retroperitoneal lymph nodes were positively enhanced by Gd-liposomes, especially after 20 min massage of the injected sites. Gd-Liposomes containing dipalmitoylphosphatidylglycerol were more effective than Gd-liposomes containing palmityl-D-glucuronide, a type of long-circulating liposomes, suggesting that liposomal accumulation in lymph node is, at least partly, mediated by the trapping of liposomes by macrophages. These data show that liposomes modified with Gd-DTPA are effective for positive enhancement of both regional and profundus lymph nodes in MR lymphography.

Animals↗

PubMed2000

Synthesis of 3-epi-6,7-dideoxyxestobergsterol A.

3-Epi-6,7-dideoxyxestobergsterol A (2), an analogue of xestobergsterol A, has been synthesized from dehydroepiandrosterone (3) in 15 steps. The key synthetic intermediate, 15beta,16alpha-dioxypregn-17(20)E-ene derivative 8, was prepared from the corresponding 15beta,16beta-epoxide 6 by treating with acetic acid and titanium tetraisopropoxide. The 23-oxo side chain was constructed stereoselectively by orthoester Claisen rearrangement of 8 followed by introduction of an isobutyl group. Basic treatment of the 15,23-diketone 12 followed by deprotection gave the title compound 2.

Animals↗

PubMed2000

A novel bisnorditerpenelactone from Mikania hirsutissima.

A novel bisnorkaurenic acid-type diterpenelactone, named mikanialactone (1), was isolated along with five known kaurenic acid-type diterpenes (2-6) from the aerial parts of Mikania hirsutissima DC (Compositae). The structure of the new bisnorditerpene was determined by spectroscopic means.

Brazil↗

PubMed2000

Mechanism of C-2 hydroxylation during the biosynthesis of 20-hydroxyecdysone in Ajuga hairy roots.

Feeding synthetic [2beta-2H]- and [2alpha-2H]-cholesterols to the hairy roots of Ajuga reptans var. atropurpurea and 2H-NMR analysis of the biosynthesized 20-hydroxyecdysone revealed that hydroxylation at C-2 proceeds with retention of configuration. Feeding [2alpha,3alpha-2H2]cholesterol followed by 2H-NMR analysis of the 2,3,22-triacetate of the resulting 20-hydroxyecdysone ruled out a mechanism which involves a partial loss of the 2alpha-hydrogen. The steric course of C-2 hydroxylation in Ajuga hairy roots is identical with that reported in the insect, Schistocerca gregaria.

Ecdysterone↗

PubMed2000

[Studies on the biosynthesis of sterol side chain in higher plants].

Campesterol (3) and dihydrobrassicasterol (4), typical C28-sterols in higher plants, are biosynthesized from a steroidal 24-ene precursor (desmosterol 1) via 24-methylenecholesterol (2) and 24-methyldesmosterol (5). A typical plant C29-sterol, sitosterol (6), is produced from 24-methylenecholesterol via isofucosterol (7) and 24-ethyldesmosterol (8). The biosynthetic mechanism, focussing stereochemical features, of these side-chain transformations has been studied in detail by feeding regio- and stereoselectively 13C- or 2H-labeled steroidal substrates to cell cultures of higher plants such as Oryza sativa, Catharanthus roseus and Morus alba. These studies allowed to correlate the metabolic origin of C-26 and C-27 of the intermediate sterols. It has been established that the 1st methylation leading to 24-methylenecholesterol from desmosterol involves a Re-face hydrogen migration from C-24 to C-25 based on unambiguous assignment of the isopropyl pro-R-Me and pro-S-Me of 24-methylenecholesterol. The 2nd methylation leading to isofucosterol was revealed to proceed in a trans-mechanism in which addition of the methyl group and elimination of the C-28 hydrogen occur on opposite faces of the original delta 24(28) plane. The double bond isomerization from delta 24(28) to delta 24(25) was found to proceed in a syn-SE2' mechanism with the pro-S-methyl group of isofucosterol becoming the (E)-methyl of 24-ethyldesmosterol. Finally, feeding studies of [E-Me-13C]- and [Z-Me-13C]-24-methyldesmosterols established that an anti-mode of hydrogen addition is operating in the conversion of 24-methyldesmosterol to campesterol and dihydrobrassicasterol. Similar studies established that 24-ethyldesmosterol is converted to sitosterol in an anti-mode of hydrogen addition. In addition, the mechanism of sterol side-chain formation in hairy roots of Ajuga reptans var. atropurpurea is briefly described.

Desmosterol↗

PubMed2000

[Chemical control of cell differentiation of human myeloleukemia K562 cell line].

Human myeloid leukemia K562 cells can be induced to differentiate to mature cells bidirectionary, i.e., hemin induces erythroid differentiation, while 12-O-tetradecanoylphorbol 13-acetate (TPA) induces differentiation to monocytes. The differentiation-inducing activity of various hemin-related compounds suggested certain structural requirements for the activity: 1) the iron moiety of hemin is not essential, and 2) the propionic acid side chains of hemin play an important role in the differentiation and induction. In addition, we have examined the influence of some bioresponse-modifying factors on hemin/protoporphyrin IX-induced differentiation of K562 cell line. Retinoids and tubulin-disruptors, themselves did not induce differentiation, enhanced hemin/protoporphyrin IX-induced differentiation of K562 cells. We also examined the possible involvement of peripheral-type benzodiazepine receptor (PBR) in hemin/protoporphyrin IX-induced differentiation on K562 cell lines. The PBR specific ligands modified hemin-induced differentiation. These results suggest a requirement for retinoids (or retinoids-like cofactors) for hemin/protoporphyrin IX-induced differentiation of K562 cells and the involvement of PBR in erythroid differentiation of K562 cell line. Further we showed that TPA suppresses hemin-induced erythroid differentiation of K562 cells, while retinoids augment it. TPA is a potent inducer of heme oxygenase (HO), which catabolizes heme to biliverdin. An HO inhibitor, tin protoporphyrin (SnPP), suppresses TPA-induced K562 cell differentiation to monocytes. It was also found that cotreatment of K562 cells with SnPP and TPA induces erythroid differentiation of K562 cells, though SnPP alone or TPA alone does not induce erythroid differentiation, suggesting a role of HO in the directional switch of differentiation.

Cell Differentiation↗

PubMed2000

Biosynthesis of PP-V, a monascorubramine homologue, by Penicillium sp. AZ.

The biosynthetic pathway of PP-V, a new monascorubramine homologue, was elucidated by 13C-labeling studies. The [1-13C] of acetate was incorporated into 2-, 3a-, 4a-, 6-, 8-, 9-, 11-, 13-, 15-, 17-, and 19-Cs of PP-V, and the [2-13C], into 3-, 4-, 5-, 8a-, 9a-, 10-, 12-, 14-, 16-, 18-, and 20-Cs. These incorporation patterns coincide with those reported in the biosynthesis of a Monascus azaphilone pigment, monascorubrin.

Journal Article↗

PubMed2000

Effect of ejaculation intervals on semen quality in cats.

The relationship between ejaculation intervals and semen quality in 4 male cats aged 3-5 years was investigated in this study. Semen was collected 10 times at intervals of every day, every other day, and every three days using an artificial vagina. Semen was collected consecutively twice on the day of semen collection, and the semen quality was examined. In semen collected every day, the number of sperm in the first collection decreased, and the frequency of immature sperm rapidly increased after the 4th day. In semen collected every other day and every three days, although the semen volume markedly varied among the animals on both first and second collections, the volume remained stable for each animal, the number of sperm was similar in the first and second collections, but was clearly larger in the first collection (p<0.01). Sperm motility and abnormality were stable among the various intervals and between the first and second collections in each animal.

Animals↗

PubMed2000

Artificial intravaginal insemination using fresh semen in cats.

To clarify the sperm count required for fertilization by artificial intravaginal insemination (AIVI), twenty-nine female cats were examined. Six male cats aged 2-12 years with normal semen quality, copulation capability, and fertility were used. In AIVI, animals received administration of 250 iu hCG once or 100 iu twice on days 2-4 of estrus to induce ovulation, and were inseminated 15, 20, or 30 hr after the initial hCG administration. The success of ovulation was judged by elevation of the peripheral progesterone level after hCG administration. AIVI was investigated at three sperm counts, 20 x 10(6) (Experiment 1), 40 x 10(6) (Experiment 2), and 80 x 10(6) (Experiment 3), with semen collected by the artificial vagina method. Semen was infused in the vagina under general anesthesia by advancing a 9 cm-long nylon probe with 1.5 mm diameter connected to a 1 ml syringe in the vagina for 3-4 cm. Ovulation was induced in 43 of 45 animals (95.6%). One of 16 animals was fertilized (conception rate: 6.6%) by AIVI in Experiment 1. In Experiments 2 and 3, conception was obtained in six of 18 animals (33.3%) and seven of nine animals (77.8%), respectively, and the mean numbers of kits were 4.0 +/- 0.4 and 3.3 +/- 0.5, respectively, and the mean numbers of kits were 4.0 +/- 0.4 (SE) and 3.3 +/- 0.5, respectively, showing no significant difference. There were no differences in the time of insemination after hCG administration and the conception rate among these groups. Our findings showed that the number of sperm required for fertilization by AIVI of fresh semen in cats was 80 x 10(6).

Animals↗

PubMed2000

Unilateral intrauterine horn insemination of fresh semen in cats.

The sperm count required were investigated to obtain a conception rate of 80% by unilateral intrauterine insemination (UIUI) of fresh semen in cats. The conception rates obtained by insemination before and after ovulation were also examined. Thirty-six female cats aged 1-7 years were used in the experiments, and the number of experimental cases was 44. Seven male cats aged 2-12 years from which semen could be collected by the artificial vagina method were used. In artificial insemination, 100 iu x 2 or 250 iu of hCG was administered on days 2-4 of estrus, and sperm were introduced into the uterine horn with a greater number of ovulations (or mature follicles) 15, 20 and 30 hr after hCG administration by laparotomy. The inseminated sperm counts were 2 x 10(6) (Exp. 1). 4 x 10(6) (Exp. 2), and 8 x 10(6) (Exp. 3). As a result, ovulation was induced in 42 of 44 cases (induction rate: 95.5%) regardless of the dosage of hCG. Conception was obtained by UIUI in two of 16 animals (conception rate: 12.5%) in the Exp. 1, five of 16 animals (31.3%) in Exp. 2, and eight of 10 animals (80.0%) in Exp. 3. Regarding the relationship between the ovulation state at insemination and conception, the conception rate obtained by insemination before ovulation was clearly higher than that obtained by insemination after ovulation (p<0.05). Regarding the number of kits compared to the number of ovulations on the inseminated side, the percentages of cases in which the number of kits exceeded the number of ovulations on the inseminated side were similar in all groups inseminated with a different number of sperm. It is therefore necessary to investigate conception rates obtained by bilateral insemination to increase the fertility rate. Based on the above findings, it was shown that the sperm count required for fertilization by UIUI is 8 x 10(6).

Animals↗

PubMed2000

Unilateral intrauterine horn insemination of frozen semen in cats.

Frozen feline semen was prepared using two types of extenders, egg yolk Tris-fructose citric acid (EYT-FC) and egg yolk sodium citrate solution (EYC), and the semen qualities after thawing and the conception rates obtained by unilateral intrauterine horn insemination (UIUI) were investigated. Cats used in the experiment were six males and 11 females aged 2-12 years (the number of experimental cases was 17). For preparation of frozen semen, semen collected by the artificial vagina method was adjusted to I x 10(8) sperm/m/ and 7% glycerol, put in 250 microl straws, and then frozen using a cell freezer. The mean sperm motility after thawing was 30.0+/-9.7 (SE) % in the semen prepared with EYT-FC and 30.0+/-3.3% in the semen prepared with EYC. Four of seven animals were fertilized by UIUI using two straws in both extenders, and the conception rate was 57.1%. The mean ratios of number of kits to the number of ovulations in the inseminated side were 61.1+/-24.5% and 30.5+/-3.4% for EYT-FC and EYC, respectively, showing that the ratio tended to be higher in the semen prepared with EYT-FC. The above findings, comparing the two extenders for preparation of frozen feline semen, showed that EYT-FC is slightly superior to EYC. To increase conception and fertility rates, it may be important to increase the sperm count for insemination and to inseminate both uterine horns.

Animals↗

PubMed2000

Involvement of Ca(2+) in antiarrhythmic effect of ischemic preconditioning in isolated rat heart.

We investigated the relationship between the effects of ischemic preconditioning (IPC) and Ca(2+) preconditioning (CPC) on reperfusion-induced arrhythmias. In the control group (noPC), Langendorff-perfused rat hearts were subjected to 5-min zero-flow global ischemia (I) followed by 15-min reperfusion (I/R). In ischemic preconditioning groups (IPC), the hearts were subjected to three cycles of 3-min global ischemia and 5-min reperfusion. In the CPC group, the hearts were exposed to three cycles of 3-min perfusion of higher Ca(2+) (2.3 mmol/l Ca(2+)) followed by 5-min perfusion of normal 1.3 mmol/l Ca(2+), and the hearts were then subjected to I/R. Verapamil was administered in several hearts of the IPC group (VR+IPC). Ventricular arrhythmias upon reperfusion were less frequently seen in the IPC and CPC groups than in the noPC and VR+IPC groups. IPC and CPC could attenuate conduction delay and enhance shortening of the monophasic action potential duration during ischemia. The ventricular fibrillation threshold measured at 1-min reperfusion was significantly higher in the IPC and CPC groups than in the noPC and VR+IPC groups. Verapamil completely abolished the salutary effects of IPC. These results demonstrate that Ca(2+) plays an important role in the antiarrhythmic effect of IPC during reperfusion.

Animals↗

PubMed2000

Recovery from Duret hemorrhage: a rare complication after craniotomy--case report.

A 44-year-old female presented with Duret hemorrhage due to transtentorial herniation by extradural hematoma as a complication after craniotomy for treatment of spontaneous middle cranial fossa cerebrospinal fluid leakage through the oval window. Brain computed tomography revealed linear hemorrhage in the midbrain and the rostral pons. She awoke after 2 weeks in a coma, despite showing ocular bobbing and bilateral intranuclear ophthalmoplegia. She was discharged from the hospital with minimal neurological defects. Duret hemorrhage is usually fatal, but this case shows that early surgical decompression is the most important factor to avoid the worst sequelae.

Adult↗

PubMed2000

[Distribution of intraglandular metastatic foci in the contralateral lobe of papillary thyroid carcinoma].

The distribution of metastatic foci in the opposite lobe has not been studied in detail despite of several reports on the high incidence of contralateral metastasis. Whether foci spread to the upper one-third of the contralateral lobe influences the choice of total or subtotal thyroidectomy. Metastasis was studied in 66 patients 11 men and 55 women aged 24-73 years (mean; 51.3), undergoing primary total thyroidectomy from 1988 to 1996. Serial blocks of the opposite lobe, approximately 5 mm thick were sliced and stained by hematoxylin-eosin. Metastases were found in 44 patients (67%). Based on the size of the primary focus, these patients were divided into group A (smaller than one-third of the lobe) and group B (greater than that of group A). The average size of the primary focus was 21 mm in group A and 36 mm in group B. The contralateral metastatic rate was 64% (14/22) in group A and 68% (30/44) in group B. The distribution of metastatic foci in the opposite lobe was studied in 44 positive patients. The spread to the upper one third occurred in 61% (27/44); 29% (4/14) in group A and 76% (23/30) in group B a significant difference (p < .003). We thus concluded that the larger the primary focus, the wider the spread of metastatic foci to the opposite lobe.

Adult↗

PubMed2000

[A case of Gerstmann-Sträussler-Scheinker disease with severe muscular atrophy and vertical gaze palsy].

Here we report a case of 56-year-old man with Gerstmann-Sträussler-Scheinker disease (GSS). He had gait disturbance, limb and truncal ataxia, dysarthria and dysphagia at the age of 53. When he developed vertical gaze palsy and dystonic posture of the neck, subcortical dementia, progressive supuranuclear palsy was suspected. Thereafter dementia rapidly progessed, and CT scan showed severe atrophy of the brain. Since severe muscular atrophy and fasciculation also appeared, and abnormality in the codon 102 of prion protein gene was found, he was diagnosed to have the classical type of GSS. GSS with vertical gaze palsy has never been reported, and involvement of the lower motor neuron is also very rare. Therefore, the present case is an atypical type of GSS.

Codon↗