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Biomedical subjects

A Ogura

Publications and source records attributed to A Ogura.

At least 19 recordsLinked to original sources
PubMed2003

New microinsemination techniques for laboratory animals.

Since the development of a reliable mouse intracytoplasmic sperm injection (ICSI) technique in 1995, microinsemination techniques have been widely applied in several laboratory species. As gametes and embryos have specific biological and biochemical features according to the species, technical improvements are necessary for successful microinsemination that subsequently leads to normal fetal development in several species. Recent advanced reproductive research involving genetic engineering often depends on microinsemination techniques that require a high degree of skill, and new human assisted reproductive technology (ART) requires experimental models using laboratory animals. The accumulation of technical improvements in these fields should accelerate the development of microinsemination techniques in mammals, including humans.

Animals↗
PubMed2003

Propofol alone, sevoflurane alone, and combined propofol-sevoflurane anaesthesia in electroconvulsive therapy.

Electroconvulsive therapy is an effective treatment for severe and medication-resistant depression. There have been no reports describing how a volatile anaesthetic affects haemodynamic responses, seizure duration, and recovery characteristics during electroconvulsive therapy. We carried out a repeated-measure crossover study to compare the effects on haemodynamic responses, seizure duration, and recovery characteristics of the following types of anaesthesia in electroconvulsive therapy: propofol alone, sevoflurane alone, and propofol combined with sevoflurane. We recruited 50 patients requiring electroconvulsive therapy for depression. For anaesthesia induction, 1.5 mg/kg propofol (condition P), 5% sevoflurane in oxygen following a vital capacity rapid inhalation induction (condition S), or 1.5 mg/kg propofol followed by 5% sevoflurane in oxygen (condition PS) was administered. Succinylcholine 1.5 mg/kg was then given. Electrical stimulation was administered after fasciculation. Measurements were obtained before anaesthesia induction (baseline), prior to succinylcholine administration, prior to electroconvulsive therapy, and at the peak after electroconvulsive therapy. After electroconvulsive therapy, peak heart rate and peak mean arterial pressure were highest in condition S. Whereas recovery time was longest in condition PS, motor seizure duration was significantly shorter than in either condition P or S. Electroencephalographic seizure duration was significantly shorter in condition PS than in condition P and significantly shorter in condition S than in condition P. Sevoflurane anaesthesia alone is most disadvantageous in terms of haemodynamics. Propofol-sevoflurane anaesthesia is advantageous in terms of haemodynamics, but disadvantageous in terms of seizure duration and recovery time. Propofol alone is most advantageous in terms of seizure duration.

Adult↗
PubMed2002

Phenotypic effects of somatic cell cloning in the mouse.

Although a variety of phenotypes and epigenetic alterations have been reported in animals cloned from somatic cells, the exact nature and consequences of cloning remain unclear. We cloned mice using fresh or short-term cultures of donor cells (cumulus cells, immature Sertoli cells, and fetal or adult fibroblast cells) with defined genetic backgrounds, and then compared the phenotypic and epigenetic characteristics of the cloned mice with those of fertilization-derived control mice. Irrespective of the nucleus-donor cell type, about 50% of the reconstructed embryos developed to the morula/blastocyst stage, but about 90% of these clones showed arrested development between days 5 and 8, shortly after implantation. Most of the clones were alive at term, readily recovered respiration, and did not show any malformations or overgrowths. However, their placentas were two- to threefold larger than those of the controls, due to hyperplasia of the basal (or spongiotrophoblast) layer. Although there was significant suppression of a subset of both imprinted and non-imprinted placental genes, fetal gene suppression was minimal. The seven imprinted genes that we examined were all expressed correctly from the parental alleles. These findings were consistent for every cell type from the midgestation through term stages. Therefore, cloning by nuclear transfer does not perturb the parent-specific imprinting memory that is established during gametogenesis, and the phenotypic and epigenetic effects of cloning are restricted to placental development at the midgestation and term stages. Twelve male mice that were born in a normal manner following nuclear transfer with immature Sertoli cells (B6D2F1 genetic background) were subjected to long-term observation. They died earlier than the genotype-matched controls (50% survival point: 550 days vs. 1028 days, respectively), most probably due to severe pneumonia, which indicates that unexpected phenotypes can appear as a result of the long-term effects of somatic cell cloning.

Animals↗
PubMed2002

Birth of offspring following transplantation of cryopreserved immature testicular pieces and in-vitro microinsemination.

BACKGROUND: Fertility protection is an urgent clinical problem for prepubertal male oncology patients who undergo either chemotherapy or radiotherapy. As these patients do not have mature sperm to be frozen, there is as yet no effective method to preserve their fertility. METHODS AND RESULTS: Single pieces of immature mouse (1.5 x 1.5 x 1.5 mm) or rabbit (2.0 x 2.0 x approximately 3.0 mm) testis were cryopreserved, thawed and transplanted into mouse testes. Histological techniques were used to determine the presence of spermatogenesis, which was restored in both mouse and rabbit testicular pieces, and led to the production of mature sperm after both cryopreservation and syngeneic or xenogeneic transplantation into mouse testes. Using sperm developed in the frozen-thawed transplants, mouse offspring were born after in-vitro microinsemination. Furthermore, rabbit offspring were obtained using rabbit sperm that developed in fresh transplants in a xenogeneic surrogate mouse. CONCLUSIONS: This approach of 'testicular tissue banking' is a promising technique for the preservation of fertility in prepubertal male oncology patients. Xenogeneic transplantation into immunodeficient mice may provide a system for studying spermatogenic failure in infertile men.

Animals↗
PubMed2002

The effects of intravenous lignocaine on haemodynamics and seizure duration during electroconvulsive therapy.

Electroconvulsive therapy (ECT) is commonly associated with acute hyperdynamic cardiovascular responses, and we hypothesize that intravenous lignocaine can blunt this response. We have measured the effect of lignocaine 1.5 mg/kg i.v. on heart rate and mean arterial pressure during electroconvulsive therapy. Furthermore, we also assessed seizure duration using both the cuff method and two-lead electroencephalography. We studied 25 patients using a randomized, double-blind, placebo-controlled crossover study design. Patients in the control group were given intravenous saline 0.075 ml/kg, and those in the lignocaine group were given intravenous lignocaine 2% 1.5 mg/kg, and this treatment was conducted one minute before intravenous propofol 1.5 mg/kg to induce unconsciousness. Succinylcholine 1.5 mg/kg was then administered intravenously and electrical stimulation was administered after fasciculation. Measurements were taken at the baseline, prior to succinycholine, prior to electroconvulsive therapy and at the peak response after electroconvulsive therapy. Intravenous lignocaine significantly reduced the increases in heart rate after electroconvulsive therapy, as compared with the placebo. The use of intravenous lignocaine was, however, associated with a remarkably shortened seizure duration. Due to the reduction in seizure duration, routine administration of intravenous lignocaine may not be advisable since it may interfere with the psychotherapeutic efficacy of electroconvulsive therapy. However, intravenous lignocaine medication for electroconvulsive therapy is potentially useful for reducing tachycardia in high-risk patients and reducing the severity of propofol injection pain in comparison with a placebo.

Adult↗
PubMed2001

Correlation of functional and ultrastructural abnormalities of mitochondria in mouse heart carrying a pathogenic mutant mtDNA with a 4696-bp deletion.

We examined the correlation of functional and structural abnormalities of cardiac mitochondria created by pathogenic mutant mtDNAs using mito-mice with hearts carrying 88% mutant DeltamtDNA4696 with a 4696 deletion. COX histochemistry, quantitative PCR analysis, and electronmicrographs showed that accumulation of 91.6% DeltamtDNA4696 in single cardiac muscle fibers induced progressive reduction of COX activity to form COX-negative fibers. Moreover, hearts carrying 88% DeltamtDNA4696 consisted of three types of cardiac muscle fibers with different functional properties, COX-positive, -negative, and -intermediate fibers, which corresponded respectively to three types of fibers with different structural properties; type A fibers containing mitochondria with only lamellar cristae, type B containing mitochondria with only tubular cristae, and type C possessing mitochondria with both lamellar and tubular cristae. These observations suggest that lamellar cristae with COX activity transform into tubular cristae without COX activity along with the accumulation of DeltamtDNA4696, which would be responsible for insufficient supply of mtDNA products required to keep the normal structure and function of mitochondrial cristae. The correlation of these structural and functional abnormalities of cristae should provide important insight into diagnosis of cardiomyopathies caused by accumulation of pathogenic mutant mtDNAs.

Animals↗
PubMed2001

Neurotoxic and neuroprotective effects of glutamate are enhanced by introduction of amyloid precursor protein cDNA.

The physiological role of amyloid precursor protein (APP), whose anomalous metabolite is a putative pathogen for Alzheimer disease, remains unclear. From the enhanced responsiveness to glutamate in cultured hippocampal neurons after the introduction of cDNA of APP695 (an isoform of APP dominant in human brain) using an adenovirus vector, we have recently raised the hypothesis that APP modulates neuronal sensitivity to glutamate. To test this hypothesis, we utilized here the unique effects of glutamate on the survival of different types of neurons. It is known that hippocampal neurons undergo deterioration in 24 h after application of glutamate in a dose-dependent manner. This vulnerability was increased in the cells transfected with adenovirus carrying cDNA of APP695. By contrast, it is known that cerebellar granule neurons require for their survival the supplementation of NMDA to the medium. The dose of NMDA required for survival was reduced after the transfection of the APP-adenovirus to cerebellar granule neurons. These enhancing effects of APP on the glutamate-induced vulnerability in hippocampal neurons and the glutamate (NMDA)-dependent survival in cerebellar neurons were blocked by glutamate receptor inhibitors, and were not seen after application of a control adenovirus carrying cDNA of beta-galactosidase. Since the effects of glutamate were enhanced in both directions, the hypothesis became more likely that one of the physiological functions of cellular APP is the regulation of glutamate receptors.

Amyloid beta-Protein Precursor↗
PubMed2001

Requirement for C3G-dependent Rap1 activation for cell adhesion and embryogenesis.

C3G is a guanine nucleotide exchange factor (GEF) for Rap1, and is activated via Crk adaptor protein. To understand the physiological role of C3G, we generated C3G knockout mice. C3G(-/-) homozygous mice died before embryonic day 7.5. The lethality was rescued by the expression of the human C3G transgene, which could be excised upon the expression of Cre recombinase. From the embryo of this mouse, we prepared fibroblast cell lines, MEF-hC3G. Expression of Cre abolished the expression of C3G in MEF-hC3G and inhibited cell adhesion-induced activation of Rap1. The Cre-expressing MEF-hC3G showed impaired cell adhesion, delayed cell spreading and accelerated cell migration. The accelerated cell migration was suppressed by the expression of active Rap1, Rap2 and R-Ras. Expression of Epac and CalDAG-GEFI, GEFs for Rap1, also suppressed the accelerated migration of the C3G-deficient cells. This observation indicated that Rap1 activation was sufficient to complement the C3G deficiency. In conclusion, C3G-dependent activation of Rap1 is required for adhesion and spreading of embryonic fibroblasts and for the early embryogenesis of the mouse.

Animals↗
PubMed2001

Epidural anesthesia with lidocaine reduces propofol injection pain.

PURPOSE: To determine whether epidural lidocaine reduces the severity of propofol injection pain compared with iv lidocaine. METHODS: A prospective, randomized double-blind clinical study was conducted in 120 female patients scheduled for elective gynecological laparotomy. A lumbar epidural catheter and an iv catheter placed in the cephalic vein of the non-dominant hand were used in all patients. Patients of the control group (Group C) were given epidural normal saline followed by iv normal saline then iv propofol. Patients of Group E were given epidural 2% lidocaine (0.08 mL.cm(-1)) followed by iv normal saline and then propofol. Patients of Group V were given epidural normal saline followed by iv 2% lidocaine (0.05 mL.kg(-1)) then propofol. Pain was scored as no pain=0, minimal pain=1, moderate pain=2, severe pain=3. RESULTS: The pain scores, in group E; 1 (0-2) and group V; 2 (0-2), were significantly lower than in group C; 2 (1-3); median (25th-75th percentile) (P <0.001). There was no difference in pain score between groups E and V The plasma lidocaine concentration 15 min after epidural lidocaine was 2.74 +/- 0.54 microg.ml(-1), compared with 1.54 +/- 0.31 microg.mL(-1) at three minutes after iv lidocaine. CONCLUSION: Epidural and iv lidocaine equally reduced the severity of propofol injection pain despite higher lidocaine plasma concentrations in epidurally administered lidocaine.

Adult↗
PubMed2001

Increase in number of functional release sites by cyclic AMP-dependent protein kinase in cultured neurons isolated from hippocampal dentate gyrus.

The enhancement of synaptic exocytosis is one form of long-term potentiation (LTP) of synaptic transmission. As possible mechanisms underlying this enhancement, increases in the release probability and/or the number of release sites are suggested. To obtain direct evidence for the increase in the number of functional release sites induced by protein kinase A (PKA) cascade, we attempted to visualize functional release sites using styryl dyes, FM4-64 and FM1-43, and investigated the effects of PKA on the release sites. A PKA activator FSK increased the number of active release sites by approximately 20-30%. A direct PKA activator, Sp-cAMPS, showed the same effect, which was blocked by a PKA inhibitor, KT5720, suggesting that this effect was mediated by PKA. This PKA-dependent increase in the number of release sites requires Ca(2+) in the bath solution, and Sr(2+) can not be a substitute for Ca(2+). Since the number of functional release sites is approximately half the total number of synaptophysin-immunoreactive sites, the PKA dependent activation of silent release sites of DG neuron terminals is suggested.

Animals↗
PubMed2001

Development of lysosomal storage in mice with targeted disruption of the beta-galactosidase gene: a model of human G(M1)-gangliosidosis.

A deficiency of lysosomal acid beta-galactosidase leads to G(M1)-gangliosidosis in humans, which progressively and profoundly affects the brain and other organs mainly in the early infantile period. We report the pathology of mice with targeted disruption of the beta-galactosidase gene. In the central nervous system, vacuolated neurons appeared in the spinal cord 3 days after birth. The vacuolation extended to neurons in the brainstem, cerebral cortex, hippocampus and thalamus and ballooning neurons became prominent with age. The vacuolation also appeared in Purkinje cells without a marked ballooning change. Reactive astrogliosis in the entire brain was marked at the terminal stage of the disease. Immunohistochemical study using anti-ganglioside G(M1) and G(A1) antibodies revealed extensive accumulation of G(M1) and G(A1) in the cerebral neurons. In the liver, however, accumulation of G(M1) was localized in the cytoplasm of hepatocytes, whereas that of G(A1) was localized in foamy macrophages and Kupffer cells. There were no significant abnormalities in the bone, bone marrow, or cornea at any stage. Although there are some phenotypic and biochemical differences between this knockout mouse and human GM1 gangliosidosis, the mouse will be a useful model for therapeutic trials for the human disease.

Animals↗
PubMed2001

Inter-mitochondrial complementation: Mitochondria-specific system preventing mice from expression of disease phenotypes by mutant mtDNA.

Here we investigated the pathogenesis of deletion mutant mitochondrial (mt)DNA by generating mice with mutant mtDNA carrying a 4696-basepair deletion (DeltamtDNA4696), and by using cytochrome c oxidase (COX) electron micrographs to identify COX activity at the individual mitochondrial level. All mitochondria in tissues with DeltamtDNA4696 showed normal COX activity until DeltamtDNA4696 accumulated predominantly; this prevented mice from expressing disease phenotypes. Moreover, we did not observe coexistence of COX-positive and -negative mitochondria within single cells. These results indicate the occurrence of inter-mitochondrial complementation through exchange of genetic contents between exogenously introduced mitochondria with DeltamtDNA4696 and host mitochondria with normal mtDNA. This complementation shows a mitochondria-specific mechanism for avoiding expression of deletion-mutant mtDNA, and opens the possibility of a gene therapy in which mitochondria possessing full-length DNA are introduced.

Animals↗
PubMed2001

Orally administered clonidine significantly reduces pain during injection of propofol.

We examined the analgesic effects of orally administered clonidine on pain induced by injection of propofol (Diprivan; 2,6-diisopropyl phenol). Female patients (n=81) were randomly allocated to one of two groups: oral clonidine (5.5 microg kg(-1)) followed by i.v. propofol and a control group given placebo followed by i.v. propofol. The median pain score in the group receiving clonidine, using a four-point scale (0=no pain, 1=minimal pain, 2=moderate pain, 3=severe pain) was 1 (0-2), significantly lower than in the control group [2 (1-3), median (25-75 percentiles), P<0.001].

Administration, Oral↗
PubMed2001

Activity of a sperm-borne oocyte-activating factor in spermatozoa and spermatogenic cells from cynomolgus monkeys and its localization after oocyte activation.

It is widely accepted that mature mammalian oocytes are induced to resume meiosis by a sperm-borne oocyte-activating factor(s) (sperm factor, SF) immediately after normal fertilization or intracytoplasmic sperm injection. The SF is most likely a soluble factor that is localized within the cytoplasm of mature spermatozoa, but the exact stage at which it appears during spermatogenesis and its localization after oocyte activation is not fully understood, except in the mouse. First, we injected mature spermatozoa and spermatogenic cells from cynomolgus monkeys into mouse oocytes to assess their oocyte-activating capacity. More than 90% of mouse oocytes were activated after injection of monkey spermatozoa. Round spermatids and primary spermatocytes (late pachytene to diplotene) also activated oocytes (93% and 79%, respectively). Injection of monkey spermatozoa and spermatids induces intracellular Ca(2+) oscillations in a pattern similar to that seen following normal fertilization. Most spermatocytes did not produce typical intracellular Ca(2+) oscillations. Second, we transferred pronuclei or cytoplasts from mouse oocytes that had been activated by monkey spermatozoa or spermatids into intact mature mouse oocytes by electrofusion in order to examine the localization of the SF after pronuclear formation. Some of the SF was localized within the pronuclei, but some stayed in the ooplasm. This study demonstrated that spermatogenic cells of cynomolgus monkeys acquire oocyte-activating capacity at much earlier stages than those of mice, and that the monkey SF has a pronucleus-directing nature, although to a lesser extent than the mouse SF.

Animals↗
PubMed2001

The effects of diltiazem on hemodynamics and seizure duration during electroconvulsive therapy.

UNLABELLED: Electroconvulsive therapy (ECT) is often associated with acute hyperdynamic responses, and we hypothesize that diltiazem can blunt this response. We measured the effect of a 10-mg dose of diltiazem on heart rate and mean arterial pressure during ECT. Furthermore, we assessed seizure duration by using both the cuff method and two-lead electroencephalogram. We studied 18 patients with a randomized, double-blinded, placebo-controlled cross-over study design. Diltiazem significantly reduced heart rate and mean arterial pressure just after medication, and it also significantly reduced the increases in these variables after ECT, as compared with the placebo. The use of diltiazem was, however, associated with a shortened seizure duration, possibly making ECT less effective. Because of the reduction in seizure duration, the routine administration of diltiazem may not be advisable because it can possibly interfere with the psychotherapeutic efficacy of ECT. However, diltiazem medication for ECT is potentially useful for reducing tachycardia and hypertension in high-risk patients. IMPLICATIONS: Diltiazem can blunt acute hyperdynamic responses after electroconvulsive therapy, but seizure duration is also significantly reduced, possibly making this therapy less effective.

Adult↗
PubMed2001

Localization of extracellular matrix receptors in ICGN mice, a strain of mice with hereditary nephrotic syndrome.

Fibrotic degeneration was examined in the kidneys of ICR-derived glomerulonephritis (ICGN) mice, a novel inbred mouse line with a hereditary nephrotic syndrome of unknown etiology considered to be a good model of human idiopathic nephrotic syndrome. In the present study, we histochemically revealed changes in accumulation of extracellular matrix (ECM) components and in localization of integrins, cellular receptors for ECM, in the kidneys of ICGN mice with the progression of renal failure. Excessive accumulation of basement membrane (laminin and collagen IV) and interstitial (type III collagen) ECM components were demonstrated in the glomeruli and tubulointerstitum of ICGN mice. Marked deposition of type I collagen and tenascin was seen only in the glomeruli of ICGN mice but not in those of ICR mice as normal controls. Increased expression of integrin alpha1-, alpha2-, alpha5- and beta1-subunits in glomeruli with fibrotic degeneration and abnormal distribution of alpha6-subunit were noted in the kidneys of ICGN mice. Excessive laminin, a ligand of alpha6beta1-integrin, was demonstrated on the tubular basement membrane, but alpha6-subunit diffusely disappeared on the basal side of the tubular epithelial cells. We presumed that abnormal integrin expression in renal tubules causes epithelial cell detachment, and consequently tubular nephropathy, and results in disorder of ECM metabolism causing excessive accumulation of ECM components in the kidneys of ICGN mice.

Albumins↗
PubMed2001

Localization of proliferative and apoptotic cells in the kidneys of ICR-derived glomerulonephritis (ICGN) mice.

The ICR-derived glomerulonephritis (ICGN) mouse is a novel inbred mouse strain with a hereditary nephrotic syndrome, considered to be a good model of human idiopathic nephrotic syndrome and develops proteinuria, hypoproteinemia and anemia. In the present study, we compared the cell kinetics in the kidneys of ICGN mice with age-matched ICR mice as normal controls. The proliferating cells were visualized by 5-bromo-2'-deoxyuridine labeling, and apoptotic cells were determined by terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphate nick end-labeling. Many proliferating epithelial cells of renal tubules, glomerular mesangial cells and tublointerstitial fibroblast-like cells were observed in the kidneys of ICGN mice, but no proliferating cells were seen in the kidneys of ICR mice. Apoptotic cells had round nuclei, and were observed only in the tubulointerstitium in the kidneys of ICGN mice but not in that of controls. The proliferation of renal tubular epithelial cells may represent a compensatory response, and that of mesangial and fibroblast-like cells may play a pathogenic role in nephrotic syndrome. Apoptosis in tubulointerstitial cells with round nuclei may have been erythropoietin-producing cells, and probably caused anemia.

Animals↗