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Biomedical subjects

M Murakami

Publications and source records attributed to M Murakami.

At least 73 records · Page 4Linked to original sources
PubMed2003

Duodenogastric reflux and Helicobacter pylori infection synergistically increase gastric mucosal cell proliferative activity in Mongolian gerbils.

BACKGROUND: Helicobacter pylori and duodenogastric reflux (DGR) are both recognized as aetiological factors in chronic gastritis and gastric carcinogenesis. In this study, a Mongolian gerbil (MG) model was used to investigate the histopathological changes in the gastric mucosa resulting from DGR and/or H. pylori infection. METHODS: One-hundred-and-eleven 7-week-old, specific-pathogen-free, male MGs were divided into four groups: normal controls, gerbils with surgically induced DGR, and H. pylori-infected gerbils with and without DGR. Gerbils were killed 4, 12 and 26 weeks after DGR surgery, their stomachs removed and sections prepared. Sections were fixed immediately in 20% phosphate-buffered formalin and subjected to haematoxylin and eosin staining, Alcian blue at pH 2.5/periodic acid-Schiff staining, and immunostaining for smooth muscle cells, H. pylori and 5'-bromo-2'-deoxyuridine (BrdU). RESULTS: The gastric mucosa of H. pylori-infected gerbils showed chronic active gastritis irrespective of DGR throughout the experimental period. The gastric mucosa of H. pylori-infected gerbils with DGR demonstrated higher BrdU labelling than in the other groups. CONCLUSIONS: In MGs, DGR and H. pylori infection synergistically increased gastric mucosal cell proliferative activity. DGR and H. pylori infection may be involved synergistically in gastric carcinogenesis by increasing cell proliferative activity.

Animals↗
PubMed2003

Dose-dependent morphological changes of intercellular canaliculi during stimulation with carbachol and isoproterenol in the isolated rat submandibular gland.

Intercellular canaliculi (IC) form a primary mixing reservoir for transcellularly and paracellularly secreted saliva whose composition depends on the degree of elevation of cytosolic Ca2+ and of cytosolic cyclic AMP concentrations caused by the secretagogues employed. In perfused rat submandibular gland (SMG), appearance of exocytosis on IC reflected the quantity of secreted mucin. Morphological observations were carried out by HR-SEM using a modified osmium maceration method on specimens treated with CCh and/or ISP. Mild secretory stimulation revealed that exocytosis did not occur simultaneously, even along the same intercellular canaliculus. Higher doses did not alter the spatial distribution of exocytosis along intercellular canaliculi but increased its temporal frequency, dose dependently. These findings lead us to conclude that, under low levels of secretory stimulation, exocytosis does not show a dose-dependent change, but that its spatial and temporal frequency changes in a dose-dependent manner.

Adrenergic beta-Agonists↗
PubMed2002

New type of vortex pinning structure effective at very high magnetic fields.

We report on a new type of correlated nanometer-scale pinning structure observed in a melt-processed (Nd0.33Eu0.38Gd0.28)Ba(2)Cu(3)O(y) (NEG-123). It consists of NEG/Ba-rich clusters in the stoichiometric NEG-123 matrix forming a lamellar array with a period of a few nanometers. These lamellas appear within regular twins, thus representing their fine substructure-sometimes straight, sometimes wavy. This new material structure correlates well with the significant enhancement of pinning at high fields, represented by irreversibility field above 14 T at 77 K (B parallel c). We believe that the new pinning medium enables one to significantly broaden the limits for high-field applications.

Journal Article↗
PubMed2002

Visualisation method of spatial interictal discharges in temporal epilepsy patients using magneto-encephalogram.

The aim of the study was to develop a method for investigating how interictal epileptic discharges in temporal epilepsy patients are activated spatially. The activity was measured using magneto-encephalography (MEG). The MEG data were used to produce a current-arrow map that reflected the topographic distribution of the electrical current for each peak epileptic waveform. A large current distribution was obtained that appeared to be contained in the limbic structure, in each temporal lobe. The large current orientation indicated two opposite directions. Furthermore, the decrease in the maximum strength of the current-arrow, depending on the medication (e.g. the decrease from 11 to 6 pT m-1 in the left temporal lobe (contralateral stimuli)), suggested that the discharge distributions could be used to verify the efficacy of medication. Thus the topographical visualisation method could be a new strategy for diagnosis in temporal epilepsy patients.

Aged↗
PubMed2002

Detection of atrial-flutter and atrial-fibrillation waveforms by fetal magnetocardiogram.

Two cases of fetal tachycardia are reported: atrial flutter and fibrillation. The waveforms from each case were detected by fetal magnetocardiograms (FMCGs) using a 64-channel superconducting quantum interference device (SQUID) system. Because the magnitude of supraventricular arrhythmia signals is very weak, two subtraction methods were used to detect the fetal MCG waveforms: subtraction of the maternal MCG signal, and subtraction of the fetal ORS complex signal. It was found that atrial-flutter waveforms showed a cyclic pattern and that atrial-fibrillation waveforms showed f-waves with a random atrial rhythm. Fast Fourier transform analysis determined the main frequency of the atrial flutter to be about 7Hz, and the frequency distribution of atrial fibrillation consisted of small, broad peaks. To visualise the current pattern, current-arrow maps, which simplify the observation of pseudo-current patterns in fetal hearts, of the averaged atrial flutter and fibrillation waveforms were produced. The map of the atrial flutter had a circular pattern, indicating a re-entry circuit, and the map of the atrial fibrillation indicated one wavelet, which was produced by a micro-re-entry circuit. It is thus concluded that an FMCG can detect supraventricular arrhythmia, which can be characterised by re-entry circuits, in fetuses.

Atrial Fibrillation↗
PubMed2002

In vitro maturation, fertilization and development of domestic cat oocytes recovered from ovaries collected at three stages of the reproductive cycle.

This study was conducted to examine the effect of the donor cat's reproductive cycle stage on in vitro maturation (IVM), in vitro fertilization (IVF), and in vitro development of oocytes recovered from ovaries that were collected and stored at 35 degrees C for a short period (1-6 h). Based on the presence or absence of follicles and corpora lutea, the ovarian pairs collected were classified into inactive, follicular, or luteal stages. Nuclear status of 161 cumulus-oocyte complexes (COCs) were examined immediately after recovery; 91.3% of the oocytes were found to be at the immature germinal vesicle (GV) stage, and 3.7% of the oocytes were at metaphase II (MII) stage. The percentage of the oocytes at the GV stage was significantly lower in the follicular stage than in the inactive stage (P < 0.01). Of the oocytes from the follicular stage, 9.1% were at MII stage. After culture for 24 h, however, the proportions of oocytes that reached metaphase I and MII were not different among the reproductive cycle stages of the ovaries collected (P > 0.05). After co-incubation with sperm, 63.1% of oocytes were fertilized, but there were no significant differences among the reproductive cycle stages of the ovaries with respect to the proportions of normal and polyspermic fertilization. However, the number of oocytes reaching cleavage stage and development to the morula and blastocyst stages from follicular stage ovaries were significantly lower (P < 0.05) than those obtained from inactive and luteal stage ovaries. These results indicate that the reproductive cycle stage of donor cat ovaries, stored at 35 degrees C, has no apparent effects on the frequencies of maturation and fertilization of oocytes, but influences developmental competence of the oocytes following IVM or IVF.

Animals↗
PubMed2002

Gastrointestinal mucoadhesive patch system (GI-MAPS) for oral administration of G-CSF, a model protein.

A new gastrointestinal mucoadhesive patch system (GI-MAPS) has been designed for the oral delivery of protein drugs. The system consists of four layered films, 3.0 x 3.0 mm2, contained in an enteric capsule. The 40 microm backing layer is made of a water-insoluble polymer, ethyl cellulose (EC). The surface layer is made of an enteric pH-sensitive polymer such as hydroxypropylmethylcellulose phthalate (HP-55), Eudragit L100 or S100 and was coated with an adhesive layer. The middle layer, drug-containing layer. made of cellulose membrane is attached to the EC backing layer by a heating press method. Both drug and pharmaceutical additives including an organic acid, citric acid, and a non-ionic surfactant, polyoxyethylated castor oil derivative (HCO-60), were formulated in the middle layer. The surface layer was attached to the middle layer by an adhesive layer made of carboxyvinyl polymer (Hiviswako 103). Fluorescein (FL), 30mg, was first used as a model drug for oral administration of GI-MAPS having different surface layers in beagle dogs. The plasma FL concentration vs. time profiles demonstrated that the targeting of the systems was obtained, because the Tmax, the time when plasma FL concentrations reaches to its maximum lelev, was 2.33+/-0.82 h for HP-55 system, 3.33+/-0.41 h for Eudragit L100 system and 5.00+/-0.00 h for Eudragit S100 system. The same three kinds of GI-MAPSs containing 125 microg of recombinant human granulocyte colony-stimulating factor (G-CSF) were prepared and orally administered to dogs and the increase in total white blood cell (WBC) counts were measured as the pharmacological index for G-CSF. Comparison with the total increase of WBCs after iv injection of the same amount of G-CSF (125 microg) indicated the pharmacological availabilities (PA) of G-CSF were 23%, 5.5% and 6.0% for Eudragit L100, HP-55 and Eudragit S100 systems. By decreasing the amount of HCO-60 and citric acid, the PA of G-CSF decreased. These results suggest the usefulness of GI-MAPS for the oral administration of proteins.

Administration, Oral↗
PubMed2002

Phylogenetic analysis of field isolates of feline calcivirus (FCV) in Japan by sequencing part of its capsid gene.

The molecular epidemiology of the infectious disease caused by feline calcivirus (FCV) in Japan was investigated by analysing the phylogenetic relationship among 21 Japanese field isolates, including the F4 strain, and 30 global isolates. Parts of the capsid gene (B-F) of the isolates were amplified by RT-PCR, and the amino acid sequences were compared with those from the global isolates. Thirty-seven and 14 out of a total of 51 isolates were clustered into two distinct genogroups, I and II respectively, by UPGMA and NJ analysis. Seven of the 21 Japanese isolates (33%) fell into group I together with 30 global isolates, while the other 14 Japanese isolates (67%) belonged to group II. The bootstrap repetition analysis of groups I and II formed by the NJ method gave a value of 99.00%. The 14 latter Japanese isolates were clearly separated from the isolates in group I, and they were different from any previously known FCV, forming a new genogroup, which implies that this lineage has been confined to Japan. Comparing the amino acid sequences shared by groups I and II, the amino acid at position 377 in B region was asparagine (Asn or Asp (NH2)) in group I, while it was lysine (Lys) in all the strains in group II. Similarly, the amino acid at position 539 in the F region was alanine (Ala) or proline (Pro) in group I, while it was valine (Val) in group II; glycine (Gly) at position 557 in group I was serine (Ser) in Group II; and phenylalanine (Phe) or leucine (Leu) at position 566 in genogroup I was tyrosine (Tyr) in group II.

Amino Acid Sequence↗
PubMed2002

Leptin inhibits stress-induced apoptosis of T lymphocytes.

Leptin, which is secreted by adipocytes, the placenta and the stomach, not only controls appetite through leptin receptors in the hypothalamus but also regulates cell-mediated immunity. In this study we have demonstrated that continuous injection of leptin prevents the reduction in lymphocyte numbers normally observed in fasted and steroid-injected mice. Consistent with leptin-induced protection, we observed up-regulation of the bcl-xL gene as a result of signal transduction via leptin receptors on lymphocytes. We suggest that leptin might contribute to the recovery of immune suppression in malnourished mice by inhibiting lymphocyte apoptosis.

Animals↗
PubMed2002

Effects of serum-free culture media on in vitro development of domestic cat embryos following in vitro maturation and fertilization.

This study was conducted to determine the adequate medium for a serum-free culture system of domestic cat embryos produced by in vitro maturation (IVM) and fertilization (IVF). Cumulusoocyte complexes recovered from cat ovaries were matured in vitro for 24 h, and then inseminated in vitro for 12 h. After insemination, the oocytes were cultured in five media [Ham's F10, Waymouth 752/1 (Waymouth), TCM199, modified Earle's balanced salt solution (MK-1) and CR1aa], each of which contained 0.4% bovine serum albumin. There were no significant differences among the rates of fertilization of oocytes cultured in five media following IVF. The rate of oocytes/embryos developed to at least the morula stage was significantly lower (p < 0.05) in Waymouth than in MK-1, TCM199 and CR1aa. Moreover, none of the embryos cultured in Ham's F10 and Waymouth developed to the blastocyst stage. There were no differences among the rates of development to the blastocyst stage of oocytes/embryos cultured in MK-1, TCM199 and CR1aa. These results indicate that the type of serum-free medium has a major impact on in vitro development of domestic cat embryos derived from IVM/IVF, and MK-1, TCM199 and CR1aa media are suitable for in vitro culture of cat embryos in a serum-free culture system.

Animals↗
PubMed2002

The microvascular augmented subdermal vascular network (ma-SVN) flap: its variations and recent development in using intercostal perforators.

In 1994 we reported the use of the microvascular augmented occipito-cervico-dorsal 'super-thin' flap for reconstruction of the cervical region in three cases. Since this preliminary report, we have performed a further 17 flaps, and the usefulness of the flap in the treatment of anterior cervical scar contractures in extensively burned patients has become apparent. Moreover, we have devised flaps with not only a narrow skin pedicle but also myocutaneous or island vascular pedicles. Various augmentation vessels, including myocutaneous perforators of the intercostal spaces in the back and chest, have also been used successfully. Here, we describe the microvascular augmented subdermal vascular network flaps that we have devised.

Adolescent↗
PubMed2002

An anatomical and clinical study of the dorsal intercostal cutaneous perforators, and application to free microvascular augmented subdermal vascular network (ma-SVN) flaps.

We report a two-part anatomical and clinical study whose aim was to map the dominant dorsal intercostal cutaneous perforators (DICPs), which are useful for microvascular augmentation of flaps raised from the skin of the back called subdermal vascular network (SVN) flaps, and to test their reliability in the clinical setting. In the anatomical arm of the study, using preserved cadavers, we macroscopically confirmed the location of DICPs, and performed micro-angiography of the dorsal skin to find each dominant DICP. In the clinical arm of the study, we confirmed the location of the dominant DICP during microvascular augmented SVN flap transfer. Postoperatively, posteroanterior radiographs of the chest were taken to locate vessel clips used to ligate the DICPs. The combined study results showed that the dominant DICP is the sixth or seventh in most instances, but there are some anatomical variations. If no dominant DICP is found in the sixth or seventh spaces, at least one DICP that is of sufficient calibre for microvascular augmentation can usually be found in the general vicinity, such as the fifth, eighth or ninth spaces. The clinical application of microvascular augmented SVN flaps, both pedicled and free, is presented.

Adult↗
PubMed2002

Relationship of fluid and mucin secretion to morphological changes in the perfused rat submandibular gland.

Transport of electrolytes/water and exocytosis are activated by elevation of the cytosolic Ca(2+) concentration and are potentiated by elevation of cytosolic cyclic AMP. To correlate mucin and fluid secretion with morphological changes, rat submandibular glands were vascularly perfused and the fluid secretion and N-acetylgalactosamine in the saliva were measured during stimulation with various concentrations of carbachol (CCh) and/or isoproterenol (ISP). Single stimulation with 1 microM CCh induced a transient increase of N-acetyl galactosamine followed by a decline to a low level during sustained stimulation. The overload of 1 microM ISP increased secretion of N-acetyl galactosamine to a higher sustained level of 40-50 microg/g-min. However, at 1 microM CCh, fluid secretion was maintained at the same level during stimulation and even overload of 1 microM ISP did not significantly affect its level, whereas addition of 0.5 microM ISP to the gland stimulated with 0.1 microM CCh increased fluid secretion. Morphological observation was carried out by HRSEM and TEM. Combination of CCh and ISP in different concentrations resulted in distinctive morphological changes which reflect fluid secretion and mucin secretion. The kinetics of ATP and creatine phosphate (PCr) were measured using P-31 NMR, which indicated that the potentiation of fluid secretion is limited under a higher level of CCh stimulation due to a limited energy supply.

Acetylgalactosamine↗
PubMed2002

Cathelicidin antimicrobial peptides are expressed in salivary glands and saliva.

The expression of antimicrobial peptides at epithelial surfaces such as skin, lung, and intestine is thought to provide protection against infection. Cathelicidin antimicrobial peptides are essential for the protection of skin against invasive bacterial infection. To determine if cathelicidins are also present in the oral cavity, we examined the expression of both mRNA and protein in mice and human saliva. The murine cathelicidin (CRAMP) was detected in the adult by reverse-transcription/polymerase chain-reaction (RT-PCR), and in embryonic, newborn, and adult tissues by in situ hybridization and immunohistochemistry. CRAMP mRNA and protein were localized to the salivary glands, specifically in acinar cells of the submandibular gland and palatine minor glands, as well as in lingual epithelium and palatal mucosa. In man, the human cathelicidin LL-37 was detected in human saliva by Western blotting. These results indicate that cathelicidins are present in the salivary system, in some oral epithelia, and in saliva, contributing to broad-spectrum defense of the oral cavity.

Animals↗
PubMed2002

Analysis of DNA fragmentation in bovine somatic nuclear transfer embryos using TUNEL.

The production of cloned animals is an inefficient process because of early or late embryonic losses. This study focused on the DNA fragmentation that occurs during embryonic development. The occurrence of DNA fragmentation was examined in bovine embryos produced by in vitro fertilization (IVF) and somatic cell nuclear transfer (NT) using the terminal deoxynucleotidyl transferase (TdT) nick-end labelling (TUNEL). IVF and NT embryos at the two-cell to blastocyst stage were stained by TUNEL for the analysis of DNA-fragmented nuclei and with propidium iodide for determination of the total number of cells. DNA fragmentation was first detected in NT embryos at the four-cell stage, but in IVF embryos at the six- to eight-cell stage. The percentage of embryos with at least one DNA-fragmented nucleus increased with the advance of the developmental stage of embryos in both IVF and NT groups. The DNA-fragmented nucleus index in NT embryos that developed beyond the four-cell stage was significantly higher (P<0.01) than that of IVF embryos at the same stage. In the both IVF and NT groups, TUNEL-labelled cells were detected in almost all blastocysts and were mainly observed in presumptive inner cell mass (ICM) cells of embryos. The DNA-fragmented nucleus index was negatively correlated with the total number of cells in NT blastocysts, but this relationship was not observed in IVF blastocysts. These results suggest that the high occurrence of DNA fragmentation observed in NT embryos may be related to early embryonic loss after transfer.

Animals↗
PubMed2001

The paracellular component of water flow in the rat submandibular salivary gland.

1. The pathway of water flow during salivary secretion by the isolated, perfused rat submandibular gland was examined using a family of homologous radiodextran molecules as probes of paracellular fluid transfer. 2. The secretion/perfusate ratio (S/P) of the secreted probes versus molecular radius during fluid secretion evoked by ACh could be resolved into two components: one that fitted a free-diffusion (Stokes-Einstein) curve and indicated diffusion through large channels, and a convective component that was linearly related to radius. 3. The convective component had a cut-off point at 0.5 nm (5 A) radius and an S/P intercept of near 1.0 at the radius of water, which indicates that most of the volume flow was paracellular. 4. The nature of such a paracellular flow is discussed together with the possible integration of this volume flow with the cellular transport of ions, resulting in an isotonic primary secretion from the gland.

Animals↗
PubMed2001

Absence of exacerbation of myocardial stunning in anesthetized dogs treated with KAD-1229, a novel hypoglycemic agent.

The effect of (+)-momocalcium bis[(2S,3a,7a-cis)-alpha-benzylhexahydro-gamma-oxo-2-isoindolinebutyrate]dihydrate (KAD-1229), a novel hypoglycemic agent with a chemical structure different from that of the sulfonylureas, on myocardial stunning was assessed in anesthetized dogs by comparison with that of glibenclamide, a sulfonylurea. Even though their hypoglycemic effects were of similar magnitude, glibenclamide (1 mg/kg, i.v.), but not KAD-1229, exacerbated the myocardial stunning induced by occlusion/reperfusion of the descending coronary artery. In a receptor-binding experiment, unlabeled glibenclamide completely inhibited [(3)H]glibenclamide binding to the myocardium, but KAD-1229 did not. These results suggest that the difference in binding properties of KAD-1229 and glibenclamide toward cardiac sulfonylurea receptors is one of the causes of their different effects on myocardial stunning. It is likely that KAD-1229 is highly specific for pancreatic sulfonylurea receptors and is speculated to be a safer hypoglycemic agent than, at least, glibenclamide.

ATP-Binding Cassette Transporters↗