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T Serikawa

Publications and source records attributed to T Serikawa.

At least 19 recordsLinked to original sources
PubMed2005

Effects of AAV-2-mediated aspartoacylase gene transfer in the tremor rat model of Canavan disease.

The tremor rat is a spontaneous epilepsy model with a seizure phenotype caused by a deletion in the aspartoacylase (ASPA) gene. The absence of ASPA expression in these animals results in undetectable levels of enzyme activity and the accumulation of the substrate N-acetyl-aspartate (NAA) in brain, leading to generalized myelin vacuolation and severe motor and cognitive impairment. In support of human gene therapy for CD, recombinant adeno-associated viral vector (AAV-2) expressing ASPA was stereotactically delivered to the tremor rat brain and effects on the mutant phenotype were measured. AAV-ASPA gene transfer resulted in elevated aspartoacylase bioactivity compared to untreated mutant animals and elicited a significant decrease in the pathologically elevated whole-brain NAA levels. Assessment of motor function via quantitative rotorod testing demonstrated that rats injected with AAV-ASPA significantly improved on tests of balance and coordinated locomotion compared to animals receiving control vectors. This study provides evidence that AAV-2-mediated aspartoacylase gene transfer to the brain improves biochemical and behavioral deficits in tremor rat mutants (tm/tm) and supports the rationale of human gene transfer for Canavan disease.

Amidohydrolases↗
PubMed2005

Sparse and wavy hair: a new model for hypoplasia of hair follicle and mammary glands on rat chromosome 17.

Mutant animals in the skin and hair have been used to identify important genes in biomedical research. We describe a new mutant rat, sparse and wavy hair (swh), that spontaneously arose in a colony of inbred WTC rats. The mutant phenotype was characterized by sparse and wavy hair, which was most prominent at age 3-4 weeks, and was inherited in an autosomal recessive manner. The swh/swh rats showed impaired gain of body weight, and their hair follicles were reduced both in number and size, associated with hypoplasia of the sebaceous glands and the subcutaneous fat tissue. Female swh/swh rats were unable to suckle their offspring. Their mammary glands were hypoplastic, and differentiation of mammary epithelial and myoepithelial cells was impaired. Linkage analysis of 579 backcross rats localized the swh locus to a .35-cM region between D17Rat131 and D17Rat50 in the distal end of rat Chr 17. The swh locus spanned the 3.7-Mb genomic region where 24 genes have been mapped and corresponded to the centromere region of the mouse Chr 2 or the region of the human Chr 10p11.1-p14. None of the genes or loci described in mouse or human hair and skin diseases mapped to these regions. These findings suggest that the rat swh is a novel mutation associated with impaired development of the skin appendages, such as hair follicles, sebaceous glands, and mammary glands, and will provide an experimental model to clarify a gene and mechanisms for development of skin appendages.

Animals↗
PubMed2001

Chromosomal assignments of mammalian genes with an acute inflammation-regulated expression in liver.

A set of acute inflammation-regulated genes expressed in liver has been assigned to rat, mouse, and human chromosomes by detecting species-specific PCR amplicons in rat(x)mouse or mouse(x)hamster somatic cell hybrids or radiation hybrids or by in silico matches of corresponding rat cDNAs to various libraries of previously assigned rat, mouse, or human genes or expressed-sequence tags. This allowed us to assign 24, 22, and 21 inflammation-regulated genes to rat, mouse, and human chromosomes, respectively. From these assignments as well as those previously determined for a larger set of genes with an acute inflammation-regulated transcription in liver, we further investigated whether such genes are clustered onto given chromosomes. A cluster was found on rat Chromosome (Chr) 6q with a conserved synteny on mouse Chr 12 and human Chr 14q13-q32, and another cluster previously reported on human Chr 1q has been extended with five further genes. Our data suggest that during an acute inflammation, a higher-order regulation may control some liver-expressed genes that share a given chromosome area.

Acute Disease↗
PubMed2001

Evaluation of the general suitability of the rat for the micronucleus assay: the effect of cyclophosphamide in 14 strains.

To evaluate the general suitability of the rat for the micronucleus assay, we conducted the assay in males of 14 different strains, 13 inbred (ACI, BN, BUF, COP, DRH, F344, IS, LEW, RCS, SHR, WAG, WKYO, WTC) and 1 outbred (SD), using cyclophosphamide as the test chemical. Cyclophosphamide at 0 (vehicle), 5, 10, or 20mg/kg per day was administered orally twice, 24h apart, to five rats per dosage group. Bone marrow and peripheral blood were collected 24h after the second treatment. All 14 strains showed a positive response to cyclophosphamide, with slight differences in sensitivity. We concluded that the rat is suitable for the micronucleus assay regardless of strain.

Administration, Oral↗
PubMed2001

Enhanced Ca(2+) influx with mossy fiber stimulation in hippocampal CA3 neurons of spontaneously epileptic rats.

This study was performed to determine whether the intracellular Ca(2+) concentration ([Ca(2+)](i)) is increased in hippocampal CA3 neurons of spontaneously epileptic rats (SER) which show both absence-like and convulsive seizures using hippocampal slices loaded with Calcium Green-1 when a weak single stimulation is given to the mossy fiber. [Ca(2+)](i) in the CA3 area was significantly increased after a single stimulus to mossy fibers in SER, while no changes were detected in normal Wistar rats. These findings suggest the existence of an abnormality in the Ca(2+) channel in the SER CA3 region and that this is probably responsible for epileptic seizures.

Action Potentials↗
PubMed2001

Attractin/mahogany/zitter plays a critical role in myelination of the central nervous system.

The rat zitter (zi) mutation induces hypomyelination and vacuolation in the central nervous system (CNS), which result in early-onset tremor and progressive flaccid paresis. By positional cloning, we found a marked decrease in Attractin (Atrn) mRNA in the brain of the zi/zi rat and identified zi as an 8-bp deletion at a splice donor site of Atrn. Atrn has been known to play multiple roles in regulating physiological processes that are involved in monocyte-T cell interaction, agouti-related hair pigmentation, and control of energy homeostasis. Rat Atrn gene encoded two isoforms, a secreted and a membrane form, as a result of alternative splicing. The zi mutation at the Atrn locus darkened coat color when introduced into agouti rats, as also described in mahogany (mg) mice, carrying the homozygous mutation at the Atrn locus. Transgenic rescue experiments showed that the membrane-type Atrn complemented both neurological alteration and abnormal pigmentation in zi/zi rats, but that the secreted-type Atrn complemented neither mutant phenotype. Furthermore, we discovered that mg mice exhibited hypomyelination and vacuolation in the CNS associated with body tremor. We conclude from these results that the membrane Atrn has a critical role in normal myelination in the CNS and would provide insights into the physiology of myelination as well as the etiology of myelin diseases.

Agouti Signaling Protein↗
PubMed2001

Genetic analysis of cataract in Ihara epileptic rat.

We analyzed the mode of inheritance of cataract in the Ihara epileptic rat (IER) by crossing experiments, and mapped cataract-related genes by linkage analysis. Cataract did not develop in the F1 animals, but it developed in both male and female animals of backcross and F2. The occurrence rate of cataract was 48.5% in the backcross progeny and 19.4% in the F2 progeny. Thus, the character was considered to be inherited by the autosomal recessive mode. We found two groups that differed according to the time of onset among the backcross and F2 progeny: an early-onset group (EOG), in which cataracts developed by about 4 months after birth, and a late-onset group (LOG), in which cataracts developed 8 months or more after birth. Linkage analysis indicated the presence of one cataract gene each on Chromosome (Chr) 8 and Chr 15, and the cataract was demonstrated to be governed by more than one gene. The gene on Chr 8 was named Catil, and that on Chr 15. Cati2. Catil was involved in the occurrence of cataract, and the conditions required for cataract to develop were Cati1i/Cati1i or Cati1i/Cati1w. However, in the cataract rats with Cati1i/ Cati1w, the allele of Cati2 was always Cati2i/Cati2i. Cati2 was involved in the timing of onset of the cataract, and the precondition for early onset was Cati2i/Cati2i.

Age of Onset↗
PubMed2001

Enhanced calcium influx in hippocampal CA3 neurons of spontaneously epileptic rats.

PURPOSE: The spontaneously epileptic rat (SER: tm/tm, zi/zi) shows both absence-like seizures and tonic convulsions. Our previous electrophysiologic studies have demonstrated that SER has abnormal excitability of hippocampal CA3 neurons, which shows a long-lasting depolarization shift by a single stimulation of mossy fibers, probably resulting from the Ca2+ channel abnorrmalities. The present study was performed to determine whether Ca2+ influx is actually enhanced in the CA3 area of SER. METHODS: Hippocampal slices were prepared from normal Wistar rats and SER aged 11-16 weeks old, when the epileptic seizures had been observed, and loaded with fura-2AM. Intracellular Ca2+ concentration ([Ca2+]i) was monitored as the ratio of fluorescence intensities excited at wavelengths of 340 and 380 nm (RF340/F380) with photometric devices. RESULTS: High K+ (10-60 mM) applied to the bath for 2 min increased [Ca2+]i in hippocampal CA1, CA3, and dentate gyrus (DG) areas of both the normal rats and SER in a concentration-dependent manner. However, the high K+-induced increase in [Ca2+]i was significantly more pronounced in the CA3 area of the SER than in that of the normal animals, whereas there were no significant differences in high K+-induced increases of [Ca2+]i in CA1 or DG between the SER and controls. The high K+-induced increases in [Ca2+]i of CA1, CA3, and DG were inhibited by nifedipine (1 to approximately 10 nM), a Ca2+ channel antagonist in both SER and controls. However, the inhibition of the high K+-induced increase in [Ca2+]i by nifedipine (1 nM) was significantly greater in the CA3 area of SER than that of controls. CONCLUSIONS: These findings suggest that Ca2+ influx through the L-type Ca2+ channels is much greater in the CA3 area of SER than in that of normal animals and is involved in the epileptic seizures of the SER.

Animals↗
PubMed2001

Molecular and phenotypic analysis of Attractin mutant mice.

Mutations of the mouse Attractin (Atrn; formerly mahogany) gene were originally recognized because they suppress Agouti pigment type switching. More recently, effects independent of Agouti have been recognized: mice homozygous for the Atrn(mg-3J) allele are resistant to diet-induced obesity and also develop abnormal myelination and vacuolation in the central nervous system. To better understand the pathophysiology and relationship of these pleiotropic effects, we further characterized the molecular abnormalities responsible for two additional Atrn alleles, Atrn(mg) and Atrn(mg-L), and examined in parallel the phenotypes of homozygous and compound heterozygous animals. We find that the three alleles have similar effects on pigmentation and neurodegeneration, with a relative severity of Atrn(mg-3J) > Atrn(mg) > Atrn(mg-L), which also corresponds to the effects of the three alleles on levels of normal Atrn mRNA. Animals homozygous for Atrn(mg-3J) or Atrn(mg), but not Atrn(mg-L), show reduced body weight, reduced adiposity, and increased locomotor activity, all in the presence of normal food intake. These results confirm that the mechanism responsible for the neuropathological alteration is a loss--rather than gain--of function, indicate that abnormal body weight in Atrn mutant mice is caused by a central process leading to increased energy expenditure, and demonstrate that pigmentation is more sensitive to levels of Atrn mRNA than are nonpigmentary phenotypes.

Age Factors↗
PubMed2001

The D allele of the angiotensin-converting enzyme gene and reperfusion-induced ventricular arrhythmias in patients with acute myocardial infarction.

The renin-angiotensin system may play a pivotal role in reperfusion ventricular arrhythmias (RVA). The purpose of this study was to investigate the association between angiotensin-converting enzyme (ACE) gene polymorphism and RVA in patients with acute myocardial infarction (AMI) in a case-control study. Patients who had undergone successful coronary intervention for AMI were enrolled (n= 127, male/female: 97/30, mean age, 62.6 years). The incidence of RVA was continuously monitored by ECG at a coronary care unit. The severity of ventricular arrhythmias was evaluated in terms of the Lown's grade and patients with a high risk of ventricular arrhythmias that may cause sudden cardiac death (Lown's grade > or =2) within 5 h of coronary intervention were defined as cases (n=59), and otherwise as controls (n=68). A receiver operating characteristic curve was used to determine the discriminatory ability of continuous variables and to produce dummy variables for use in a logistic regression analysis. Cases had a significantly higher body mass index, higher maximal levels of serum creatine kinase, and a shorter time preceding coronary intervention than controls. The severity of coronary atherosclerosis was similar between the 2 groups. The frequency distribution of ACE genotypes in cases differed from that in controls (II/ID/DD: 22.0%/52.6%/25.4% vs 44.1%/41.4%/14.7%, p<0.05, by the Mantel-Haenzel chi-square test). The ACE-D allele had additive and dominant effects with regard to the occurrence of significant ventricular arrhythmias after adjusting for other risk factors. The ACE-D allele may play a pivotal role in sudden cardiac death in patients with AMI.

Accelerated Idioventricular Rhythm↗
PubMed2001

Linkage mapping of the mouse nephrosis (nep) gene to chromosome 15.

ICGN is a partially inbred strain of mice with nephrotic syndrome caused by spontaneous glomerular lesion. It has been reported that the albuminuria in ICGN mouse was controlled by at least a single autosomal recessive gene (nep). In this study, we mapped the nep locus by linkage analysis of backcross progeny between ICGN and MSM mice using DNA pooling method. The linkage analysis revealed that the nep locus was localized on the distal part of chromosome 15.

Animals↗
PubMed2000

A new cationic liposome for efficient gene delivery with serum into cultured human cells: a quantitative analysis using two independent fluorescent probes.

Cationic liposomes are useful to transfer genes into eukaryotic cells in vitro and in vivo. However, liposomes with good transfection efficiency are often cytotoxic, and also require serum-free conditions for optimal activity. In this report, we describe a new formulation of cationic liposome containing DC-6-14, O,O'-ditetradecanoyl-N-(alpha-trimethylammonioacetyl)diethan olamine chloride, dioleoylphosphatidylethanolamine and cholesterol for gene delivery into cultured human cells. This liposome, dispersed in 5% serum-containing growth medium, efficiently delivered a plasmid DNA for GFP (green fluorescent protein) into more than 80% of the cultured human cell hybrids derived from HeLa cells and normal fibroblasts. Flow cytometric analysis revealed that the efficiency of the GFP gene expression was 40-50% in a tumor-suppressed cell hybrid, while it was greatly reduced in the tumorigenic counterpart. The enhanced GFP expression in tumor-suppressed cell hybrids was quantitatively well correlated with a prolonged presence of the plasmid DNA, which had been labeled with another fluorescent probe, ethidium monoazide, within the cells. These results suggest that a newly developed cationic liposome is useful for gene delivery in serum-containing medium into human cells and the stability of the plasmid DNA inside the cell is a crucial step in this liposome-mediated gene expression. The mechanisms by which cationic liposome mediates gene transfer into eukaryotic cells are also discussed.

Cations↗
PubMed2000

Epileptic seizures induced by N-acetyl-L-aspartate in rats: in vivo and in vitro studies.

Tremor rat (tm/tm), the parent strain of spontaneously epileptic rat (SER: zi/zi, tm/tm), exhibits absence-like seizures characterized by 5-7 Hz spike-wave-like complexes on cortical and hippocampal electroencephalograms (EEG) after 10 weeks of age, prior to development of convulsive seizures. Recently, this animal model has been demonstrated to display a genomic microdeletion within the critical region of tm, where aspartoacylase hydrolyzing N-acetyl-L aspartate (NAA) is located, besides showing the ability to accumulate NAA in the brain. Therefore, the present study was performed to determine the involvement of NAA in the induction of epileptic seizures. When NAA (4 micromol) was applied intracerebroventricularly (i.c.v.) to normal Wistar rats, 4-10 Hz polyspikes and/or spike-wave-like complexes followed by absence-like seizure before persistent 1-5 Hz waxing high-voltage after-discharges were observed on cortical and hippocampal EEG. At a higher dose (8 micromol), NAA induced convulsive seizures. The absence-like seizures with polyspikes and/or spike-wave-like complexes on the EEG were also observed with i.c.v. NAA in premature tremor rats without seizures. The NAA-induced seizures in normal rats were antagonized by i.c.v. glutamic acid diethyl ester, a non-selective glutamate receptor antagonist. In addition, NAA applied to the bath rapidly induced a long-lasting depolarization concomitantly with repetitive firings in hippocampal CA3 neurons of normal rat brain slice preparations. These findings suggest that NAA is involved in the induction of absence-like seizures and/or convulsion, probably via glutamate receptors.

Animals↗
PubMed2000

Genetic mapping of the rat mutation creeping and evaluation of its positional candidate gene reelin.

We have previously described a rat autosomal recessive mutation, creeping (cre), causing severe ataxia and disarrangement of neuronal cells in the central nervous system. The mutant strain has recently been successfully inbred, named Komeda Zucker creeping (KZC) rat. In the present study, we have performed a genetic analysis of the creeping mutation, and mapped it to rat Chromosome (Chr) 4. Comparative mapping, together with the similarity of the phenotype, suggested that the creeping mutation is homologous to the mouse reeler mutation. In fact, reelin expression was markedly reduced in the homozygous mutant (cre/cre) animals compared with the normal littermates. Thus, the KZC rat should become a useful biological model with a novel mutation in the reelin gene.

Animals↗
PubMed2000

Accumulation of N-acetyl-L-aspartate in the brain of the tremor rat, a mutant exhibiting absence-like seizure and spongiform degeneration in the central nervous system.

The tremor rat is a mutant that exhibits absence-like seizure and spongiform degeneration in the CNS. By positional cloning, a genomic deletion was found within the critical region in which the aspartoacylase gene is located. Accordingly, no aspartoacylase expression was detected in any of the tissues examined, and abnormal accumulation of N-acetyl-L-aspartate (NAA) was shown in the mutant brain, in correlation with the severity of the vacuole formation. Therefore, the tremor rat may be regarded as a suitable animal model of human Canavan disease, characterized by spongy leukodystrophy that is caused by aspartoacylase deficiency. Interestingly, direct injection of NAA into normal rat cerebroventricle induced 4- to 10-Hz polyspikes or spikewave-like complexes in cortical and hippocampal EEG, concomitantly with behavior characterized by sudden immobility and staring. These results suggested that accumulated NAA in the CNS would induce neuroexcitation and neurodegeneration directly or indirectly.

Amidohydrolases↗
PubMed2000

Chromosomal mapping of genes for epilepsy in NER: a rat strain with tonic-clonic seizures.

PURPOSE: NER is a mutant rat strain that exhibits spontaneous tonic-clonic convulsions accompanied by epileptic discharges on ictal EEG and serves as a model for generalized tonic-clonic seizures in humans. Our previous experiments have suggested that a major autosomal recessive gene and several minor genes regulate the inheritance of tonic-clonic seizures in NER. The purpose of this study was to confirm the mode of inheritance and to locate the causative genes for epilepsy in NER on the rat genetic map. METHODS: We developed F1 hybrid (F1) and reciprocal back-cross progenies of NER with a seizure-resistant strain, F344, and evaluated their seizure susceptibility under tossing-stimulated and nonstimulated conditions. Backcross animals were genotyped using simple sequence length polymorphism markers for polymerase chain reactions. Linkage between seizure susceptibility and marker loci was analyzed by chi2 statistic tests and by the computer programs MAPMAKER/EXP and MAPMAKER/QTL. RESULTS: Under tossing-stimulating conditions, tonic-clonic seizures were provoked in 90% of NER and 66% of (F1 x NER) backcross animals, but no seizures occurred in the F344, F1, or (F1 x F344) backcross animals. Routine monitoring of nonstimulated animals revealed spontaneous tonic-clonic convulsions in 100% of NER and 64.2% of (F1 x NER) backcross animals, but no seizures in F344 or F1. Gender effect on seizure susceptibility was negligible in (F1 x NER) backcross in both conditions. Preliminary genome-wide scanning and subsequent precise location of the causative genes revealed seizure susceptibility loci, designated Ner1 and Ner2, on rat chromosomes 1 and 3, respectively. CONCLUSIONS: Ner1 is a locus that controls the inheritance of spontaneous tonic-clonic seizures in an autosomal recessive mode, whereas Ner2 affects the occurrence of tossing-induced seizures. Orthologous genes in the vicinity of these loci may be related to epileptogenesis in other species, including humans.

Animals↗
PubMed2000

Mapping of four simple sequence repeat (SSR) markers on rat chromosome 4.

We previously reported that several markers on rat chromosome (Chr) 4 cosegregated with the occurrence of cerebral stroke and brain edema in stroke-prone spontaneously hypertensive rats (SHRSP). To obtain insights into the positional candidate genes for stroke susceptibility in this region, we mapped four genes, Taurine transporter (Tau), tumor necrosis factor receptor (Tnfr), GABA transporter (Gat1) and glucose transporter-3 (Glut3) genes, using newly developed simple sequence repeat (SSR) markers on rat Chr 4. We isolated the SSRs for the genes either by screening a rat genomic library or by searching the GenBank database. By linkage analysis using two sets of backcrosses, Gat1 and Tnfr were mapped in the region associated with stroke, while Taut was located distant from the region. The Glut3 locus was also assigned to rat Chr 4 using a rat x mouse hybrid clone panel. These results indicated that the Tnfr, Gat1 and Glut3 genes were good positional candidates for the stroke susceptibility in SHRSP, suggesting that further evaluation of these genes by functional studies could prove useful.

Animals↗