Biomedical subjects

M Nishihara

Publications and source records attributed to M Nishihara.

At least 19 recordsLinked to original sources

PubMed2004

High expression of interleukin-1beta in the corneal epithelium of MRL/lpr mice is under the control of their genetic background.

MRL/Mp mice bearing the Fas deletion mutant gene, lpr (MRL/lpr), spontaneously develop polyarthritis, sialoadenitis and dacryoadenitis, resembling rheumatoid arthritis (RA), and also corneal involvement such as keratopathy and scleritis, which is a major complication in RA patients. In this study, we found that the expression levels of IL-1beta and MMP-1 mRNAs in cornea were high in both MRL/lpr and MRL/Mp-+/+ strains of mice at an age younger than when they develop any inflammatory lesions. This was not true of other inbred strains, even those bearing the lpr gene, and also not of (NZB x NZW) F1 lupus mice. There was no significant difference in the expression of IL-1alpha and TGFbeta in cornea in these strains. Using crosses between MRL/lpr and C3H/HeJ-lpr/lpr (C3H/lpr) mice, at least the expression of IL-1beta was found to be under the control of the MRL genetic background, likely with a recessive mode of inheritance. Considering that IL-1beta in cornea was detected particularly in the epithelial layer, the high expression of IL-1beta in cornea is most likely involved in the genetic predisposition for corneal involvement and possibly also for arthritis in an MRL strain of mice.

Animals↗

PubMed2003

Successful laparoscopic Ladd's procedure and appendectomy for intestinal malrotation with appendicitis.

We successfully performed a laparoscopic Ladd's procedure and an appendectomy in a 15-year-old girl with intestinal malrotation and appendicitis. She had tenderness and rebound pain in the umbilicus and left lower abdominal quadrant. Blood analysis revealed a moderate inflammatory response. Enhanced computerized tomography (CT) scanning revealed a whirl-like pattern and a superior mesentric vein (SMV) rotation sign in the mesentry of the small intestine. A swollen appendix was seen just below the umbilicus. An upper gastrointestinal (GI) radiological series confirmed agenesis of Treitz's arch. The patient was diagnosed as having a nonrotation type of malformation accompanied by acute appendicitis. She underwent a laparoscopic Ladd's procedure, an appendectomy, peritoneal lavage, and drainage. The technique for this procedure and its effectiveness are briefly discussed.

Adolescent↗

PubMed2003

Correlation between spontaneous feeding behavior and neuropeptide Y profile in the third ventricular cerebrospinal fluid of goats.

Feeding behavior is regulated by neural signals in the hypothalamus, but secretory activities of these signals in vivo and their relationship with spontaneous feeding remain to be solved. In the present study, we investigated the correlation between neuropeptide Y (NPY) and somatostatin (SRIF) profiles in cerebrospinal fluid (CSF) and spontaneous feeding behavior in goats. CSF samples were collected every 15 min for 8 h from the third ventricle and feeding behavior was observed throughout the experimental period. The spontaneous feeding behavior, the mean duration of which was 58 min, occurred with an interval of 146 min. NPY in the CSF fluctuated in an episodic fashion with a 145 min interval. Each NPY episode was followed by spontaneous feeding with a time lag of 24 min. SRIF levels in CSF changed more frequently in a pulsatile manner and were related to neither NPY profiles nor feeding behavior. These results suggest that NPY, but not SRIF, is a physiological signal to drive feeding in goats.

Animals↗

PubMed2002

Production of 5,8,11-eicosatrienoic acid by a delta5 and delta6 desaturation activity-enhanced mutant derived from a delta12 desaturation activity-defective mutant of Mortierella alpina 1S-4.

Enhanced production of 5,8,11-eicosatrienoic acid (Mead acid, 20:3omega9) was attained with a mutant fungus, Mortierella alpina JT-180, derived from delta12 desaturation activity-defective and delta6 desaturation activity-enhanced M. alpina M209-7. Production of 20:3omega9 by JT-180 was 1.4 times greater than that of the parent strain M209-7. This is thought to be due to its enhanced Delta5 desaturation activity, which was 3.3 times higher than that of M209-7. In both strains, 78.5-80.4% of the total lipids comprised triacylglycerol (TG), and 76.6-79.0% of 20:3omega9 was present in TG. Comparing the fatty acid compositions among various lipid species, the highest percentages (24.1-37.6%) of 20:3omega9 in total lipids were found in phosphatidylcholine. For optimization of 20:3omega9 production by JT-180, a glucose concentration of 4% in the culture medium and shifting of the growth temperature from 28 degrees C to 20 degrees C on the 2nd day were shown to be effective. Under optimal conditions, 20:3omega9 production by JT-180 reached 1.92 g/l culture medium in a 10-l jar fermentor (corresponding to 81.5 mg/g dry mycelia and 18.3% of total fatty acids), which is greater than that reported previously from M209-7 (1.65 g/l).

8,11,14-Eicosatrienoic Acid↗

PubMed2002

Subthalamic locomotor region is involved in running activity originating in the rat ventromedial hypothalamus.

We have previously shown the involvement of the ventromedial nucleus of the hypothalamus (VMH) in inducing running behavior. Stimulation of kainate (KA)-type glutamate receptors in the unilateral VMH of the rat exclusively elicited stereotyped running behavior. However, the neural pathways or functional connections of the VMH neurons involved in the running activity are yet to be elucidated further. In this study we examined whether the subthalamic locomotor region (SLR) is involved in the expression of the running activity originating in the VMH. The multiunit activity (MUA) in the ipsilateral SLR was significantly increased by KA injection into the VMH of urethane-anesthetized animals. Concomitant injection of 6,7-dinitroquioxalline-2,3-dione (DNQX, a KA-type glutamate receptor antagonist) with KA blocked this change in the MUA. Unilateral pre-injection of either kynurenate (non-selective glutamate receptor antagonist), D-2-amino-5-phosphonovalerate (AP5, an NMDA-type glutamate receptor antagonist) or DNQX into the SLR blocked the expression of the running activity induced by KA injection into the ipsilateral VMH. Results from the present study suggest that communication between KA-sensitive efferents from the VMH to glutamatergic pathways acting via NMDA and non-NMDA receptors in the SLR may underlie expression of running behavior originating in the VMH.

Animals↗

PubMed2002

Impaired insulin signaling in the liver of transgenic rats with low circulating growth hormone levels.

GH is known to regulate glucose and lipid metabolism as well as body growth. Controversy exists as to whether GH-deficient adults are indeed insulin sensitive or insulin resistant. In GH-deficient animal models, however, no clear observation indicating insulin resistance has been made, while increased insulin sensitivity has been reported in those animals. We have produced human GH (hGH) transgenic rats characterized by low circulating hGH levels and virtually no endogenous rat GH secretion. Although the body length of the transgenic rat is normal, they develop massive obesity and insulin resistance, indicating that the transgenic rat is a good model for the analysis of insulin resistance under GH deficiency. In this study, we have examined how GH deficiency affects the early steps of insulin signaling in the liver of the transgenic rat. Circulating glucose and insulin concentrations were significantly higher in the transgenic rats than in their littermates. In addition, impaired glucose tolerance was observed in the transgenic rat. The amount of insulin receptor was smaller in the liver of the transgenic rat, resulting in decreased tyrosine phosphorylation in response to insulin stimulation. The amounts of insulin receptor substrate-1 and -2 (IRS-1 and -2) and insulin-stimulated phosphorylation of IRSs were also smaller in the transgenic rat. Despite the decrease in tyrosine phosphorylation levels of IRSs being mild to moderate (45% for IRS-1 and 16% for IRS-2), associated phosphatidylinositol 3-kinase (PI3-kinase) activity was not increased by insulin stimulation at all in the transgenic rat. To elucidate whether this discrepancy resulted from the alteration in binding of the p85 subunit of PI3-kinase to phosphotyrosine residues of the IRSs, we determined the amount of p85 subunit in the immunocomplexes with anti-phosphotyrosine antibody. Insulin did not affect the amount of p85 subunit associated with phosphotyrosine in the transgenic rats, while it significantly increased in the controls, indicating that alteration may have occurred at the sites of phosphorylated tyrosine residues in IRSs. These results suggest that GH deficiency in the transgenic rat leads to impairment in at least the early steps of insulin signaling in the liver with a resultant defect in glucose metabolism.

Analysis of Variance↗

PubMed2001

Induction of granulin precursor gene expression by estrogen treatment in neonatal rat hypothalamus.

Our previous research has demonstrated that androgen treatment during the perinatal period increases granulin (grn) precursor mRNA levels in the neonatal rat hypothalamus. To elucidate whether exogenous estrogen increases grn mRNA in the neonatal hypothalami, expression of grn gene in the neonatal hypothalamus was studied by the competitive reverse transcription-polymerase chain reaction method. At 6 and 10 days of age, grn gene expression was significantly increased in the hypothalamus of pups whose dam has been dietarily administrated ethinyl estradiol from day 15 of gestation to the day of sampling. The subcutaneous injection of estradiol benzoate to neonatal rats at 2 days of age significantly increased grn gene expression on day 10. It was shown that estrogen, as well as androgen, was able to induce grn gene expression in the neonatal hypothalamus.

Administration, Oral↗

PubMed2001

Detection of transgene in progeny at different developmental stages following testis-mediated gene transfer.

We recently reported that exogenous DNA injected into testis as a liposome complex can be transferred into the egg via sperm by natural mating and integrated in the genome (testis-mediated gene transfer: TMGT). Here, we studied the efficiency of each of the several liposomes in associating foreign DNA with sperm, the expression of an introduced gene in early embryos, and the presence of the DNA in fetuses and pups at different ages. The CMV/beta-actin/EGFP fusion gene, encapsulated with different liposomes, was injected into rat testis, and spermatozoa in the cauda epididymis were obtained 1, 4, and 14 days after injection. We tested each of the 8 liposomes, and found that only 2, DMRIE-C and SuperFect, led to the detection of foreign DNA on all of the days examined, with relatively higher ratios of rats having positive sperm. By means of TMGT using either of those two liposomes, more than 80% of morula-stage embryos expressed EGFP, as observed by fluorescence microscopy. Then we detected introduced DNA in the progeny by PCR and Southern dot blot, and found that the ratio of animals carrying the foreign DNA decreased as they developed, and that only a part of postpartum progeny were foreign-DNA-positive with high incidence of mosaicism. These results suggest that, although, the success rate is still limited, foreign DNA could be integrated into the genome of the progeny by TMGT at least under specific experimental conditions, the efficiency of which depends largely on the characteristics of the liposome. The results also suggest that TMGT could be applicable to fetal gene therapy as well as to the generation of transgenic animals.

Animals↗

PubMed2001

Ghrelin in domestic animals: distribution in stomach and its possible role.

Ghrelin, a novel growth-hormone-releasing acylated peptide, was recently isolated from rat and human stomachs. In rat, peripheral or central administration of ghrelin stimulates the secretion of growth hormone (GH) from the pituitary gland. Recent work suggests that ghrelin plays an important role in energy homeostasis, body weight, and food intake. We examined the distribution of cells immunoreactive to ghrelin in the stomachs of domestic animals and rats, using a polyclonal antibody for the N-terminal fragment of rat ghrelin [1-11]. We measured the plasma levels of ghrelin before and after feeding in cows, and GH levels after central administration of ghrelin in Shiba goats, to elucidate the possible role of ghrelin. Immunostained cells were widely distributed from the neck to the base of the oxyntic gland in all animals. The plasma ghrelin concentration in cows decreased significantly 1 h after feeding, and then recovered to pre-feeding levels. Administration of ghrelin into the third ventricle in Shiba goats dramatically increased the plasma GH concentration dose-dependently. These results suggest that ghrelin plays an important role in GH secretion and feeding regulation in domestic animals.

Animals↗

PubMed2001

Production of antimicrobial defensin in Nicotiana benthamiana with a potato virus X vector.

A recombinant plasmid, pTXS.TH, was constructed to express the gene-encoding wasabi (Wasabia japonica) defensin with the potato virus X (PVX) vector. pTXS.TH allows the expression of defensin in the host Nicotiana benthamiana, and the defensin protein WT1 can be purified from virus-infected leaves by heat treatment and affinity chromatography. WT1 exhibits strong antifungal activity toward the phytopathogenic fungi Magnaporthe grisea (50% inhibitory concentration [IC50] = 5 microg/ml) and Botrytis cinerea (IC50 = 20 microg/ml) but is weakly active against the phytopathogenic bacterium Pseudomonas cichorii. This virus-mediated expression system is a rapid and efficient method to produce and characterize antimicrobial proteins in plants. It is particularly useful for the study of proteins that are difficult to produce with other expression systems.

Anti-Infective Agents↗

PubMed2001

Expression of ovarian 20alpha-hydroxysteroid dehydrogenase in rat thymus.

Ovarian 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD), which converts progesterone to a derivative devoid of biological activity, plays a crucial role in achieving the short estrous cycle in rats. Although 20alpha-HSD activity has also been demonstrated in the thymus, its molecular nature, function, and regulation of expression have yet to be determined. In the present study we investigated if 20alpha-HSD activity in the thymus originates in a transcript identical to that expressed in the ovary. RT-PCR analysis indicated the expression of 20alpha-HSD mRNA in rat thymus, and sequencing of the PCR product showed 100% identity to ovarian 20alpha-HSD cDNA. Immunohistochemical study using anti-rat ovarian 20alpha-HSD antibody demonstrated the expression of 20alpha-HSD protein in the thymus. The 20alpha-HSD-expressing cells in the thymus seemed to be some type of lymphocyte by their morphology. These results suggest that the same molecular species as ovarian 20a-HSD is expressed in thymic lymphocytes. Therefore, 20alpha-HSD may play a role in T-lymphocyte proliferation and differentiation processes.

20-Hydroxysteroid Dehydrogenases↗

PubMed2001

Usefulness of volume-rendered three-dimensional computed tomographic angiography for surgical planning in treating unruptured paraclinoid internal carotid artery aneurysms.

Paraclinoid internal carotid artery aneurysms are difficult to treat and difficult to visualize by using DSA, MRA, or surface-rendered 3D-CTA. Because those aneurysms are surrounded by bone, the dural ring (proximal and distal), the optic nerve, the oculomotor nerve, and the cavernous sinus. This report represents the first attempt to assess the verification of volume-rendered 3D-CTA for surgical planning in treating paraclinoid internal carotid artery aneurysms. From January, 1996 to October, 2001, we treated 15 cases of unruptured paraclinoid internal carotid artery aneurysms at Kobe University Hospital. Twelve of the patients were women and three were men, ranging age from 33 to 70 (55.7 /10.3). We studied used volume-rendered 3D-CTA to examine five patients and surface-rendered 3D-CTA for ten. Volume-rendered 3D-CTA allowed observation of the aneurysms and their necks and the surrounding structures in all cases (P<0.001), while surface-rendered 3D-CTA allowed partial observation of the aneurysms in 5 cases (50%). Volume-rendered 3D-CTA enabled virtual removal of bones by using the clip-plane editing and allowed the aneurysms to be viewed from various angles. When the pterional approach is used and the neck of the aneurysm is found to be remote from the anterior clinoid process, the anterior clinoid process need not be removed. In conclusion, for paraclinoid internal carotid artery aneurysms, volume-rendered 3D-CTA is superior to surface-rendered 3D-CTA, MRA and digital subtraction angiography in terms of visualization of the aneurysm and surrounding bones. It was great help for surgical planning in treating paraclinoid internal carotid artery aneurysms.

Adult↗

PubMed2000

CTP:2,3-di-O-geranylgeranyl-sn-glycero-1-phosphate cytidyltransferase in the methanogenic archaeon Methanothermobacter thermoautotrophicus.

CDP-2,3-di-O-geranylgeranyl-sn-glycerol synthase (CDP-archaeol synthase) activity was discovered in the membrane fraction of the methanoarchaeon Methanothermobacter thermoautotrophicus cells. It catalyzed the formation of CDP-2,3-di-O-geranylgeranyl-sn-glycerol from CTP and 2,3-di-O-geranylgeranyl-sn-glycero-1-phosphate (unsaturated archaetidic acid). The identity of the reaction product was confirmed by thin layer chromatography, fast atom bombardment-mass spectroscopy, chemical analysis, and by UV spectroscopy. One mole of the product was formed from approximately 1 mol of each of the reactants. The enzyme showed maximal activity at pH 8.5 and 55 degrees C in the presence of Mg(2+) and K(+) ions. By in vivo pulse labeling of phospholipids with (32)P(i), CDP-archaeol was found to be an intracellular intermediate. A cell-free homogenate of M. thermoautotrophicus, when incubated with l-serine, converted the product of CDP-archaeol synthase reaction to a product with the same chromatographic mobility as archaetidylserine. It was concluded from these results that both CDP-archaeol and CDP-archaeol synthase were involved in cellular phospholipid biosynthesis. Among various synthetic substrate analogs, both enantiomers of unsaturated archaetidic acid possessing geranylgeranyl chains showed similar levels of activity, while archaetidic acid with saturated or monounsaturated isoprenoid or straight chains was a poor substrate, despite having the same stereostructure as the fully active substrate. The ester analogs with geranylgeranioyl chains showed significant activities. These results suggest that the enzyme dose not recognize ether or ester bonds between glycerophosphate and hydrocarbon chains nor the stereostructure of the glycerophosphate backbone but mainly targets substrates with geranylgeranyl chains.

Catalysis↗

PubMed2000

Genome analysis of collagen disease in MRL/lpr mice: polygenic inheritance resulting in the complex pathological manifestations.

MRL/MpJ-lpr/lpr (MRL/lpr) mice develop collagen disease involving vasculitis, glomerulonephritis, arthritis and sialoadenitis, each of which has been studied as a model for polyarteritis, lupus nephritis, rheumatoid arthritis and Sjögren's syndrome, respectively. In the previous studies, we observed genetic segregation of these complex pathological manifestations throughout the genome recombination with a C57Bl/6-lpr/lpr or a C3H/HeJ-lpr/lpr (C3H/lpr) strain of mice which rarely develops such lesions, indicating that development of collagen disease is dependent on an MRL host genetic background. To clarify the mode of inheritance and the gene loci affecting four types of the lesions in MRL/lpr mice; vasculitis, glomerulonephritis, arthritis and sialoadenitis, a genetic dissection of the lesions was carried out by using MRL/lpr, C3H/lpr, (MRL/lprxC3H/lpr) F1 intercross, and MRL/lprx(MRL/lprxC3H/lpr) F1 backcross mice. Definition of each lesion was performed by histopathology under light microscopy, and genomic DNA of the backcross mice were subjected to association studies by chi-square analysis for determining which polymorphic microsatellite locus occurs at higher frequency among affected compared to unaffected individuals for each lesion. We observed that gene loci recessively associated with each lesion were mapped on different chromosomal positions. We conclude that each of four types of the lesions in MRL/lpr mice is under the control of different set of genes, suggesting the complex pathological manifestations of collagen disease result from polygenic inheritance.

Animals↗

PubMed2000

Significant evidence for linkage of mite-sensitive childhood asthma to chromosome 5q31-q33 near the interleukin 12 B locus by a genome-wide search in Japanese families.

Childhood-onset asthma is frequently found in association with atopy. Although asthmatic children may develop IgE antibodies against variety of allergens, asthma is associated primarily with allergy to house-dust mites, molds, or other allergens. In this study, we conducted a genome-wide linkage search in 47 Japanese families (197 members) with more than two mite-sensitive atopic asthmatics (65 affected sib-pairs) using 398 markers. Multipoint linkage analysis was carried out for atopic asthma as a qualitative trait using the MAPMAKER/SIB program. We observed significant evidence for linkage with maximum lod scores (MLS) of 4.8 near the interleukin 12 B gene locus on chromosome 5q31-q33. In addition, suggestive evidence on 4q35 with MLS = 2.7 and on 13q11 with MLS = 2.4 was obtained. The other possible linkage regions included 6p22-p21.3 (MLS = 2.1), 12q21-q23 (MLS = 1.9), and 13q14.1-q14.3 (MLS = 2.0). Many of the linkage loci suggested in this study were at or close to those suggested by genome-wide studies for asthma in Caucasian populations. The present study suggests the contribution of the interleukin 12 B gene or nearby gene(s) to mite-sensitive atopic asthma and a considerable number of genetic variants common across Caucasians and Japanese populations contributing to asthma, although the relative importance of various variants may differ between the groups.

Adolescent↗

PubMed2000

Requirement of the Fas ligand-expressing luteal immune cells for regression of corpus luteum.

Apoptosis in corpus luteum (CL) is induced by prolactin (PRL) in female rats. PRL-induced apoptosis in CL is mediated by the Fas/Fas ligand (FasL) system. The CL consists of steroidogenic and non-steroidogenic cells, including immunocytes. Fas mRNA was detected only in the luteal steroidogenic cells, and FasL mRNA was expressed only by the non-steroidogenic CD3-positive luteal immunocytes. Removing the luteal immune cells from the luteal cells inhibited PRL-induced luteal cell apoptosis effectively. Thus, FasL-expressing non-steroidogenic luteal immunocytes are required for PRL-induced luteal cell apoptosis and heterogeneous induction of apoptosis by Fas/FasL in CL.

Animals↗

PubMed2000

Enzymatic determination of sn-glycerol-1-phosphate.

A sensitive and positive colorimetric method for quantification of sn-glycerol-1-phosphate (G-1-P) is described. The use of G-1-P-specific dehydrogenase from Methanobacterium thermoautotrophicum and a tetrazolium salt (an NAD-recycling system) allowed a positive measurement of G-1-P, and caused an increase in sensitivity. Because G-1-P is not only the backbone of the ether glycerolipids in Archaea (formerly archaebacteria) but also the component of lipoteichoic acid polymers from some Gram-positive bacteria, membrane-derived oligosaccharide from Escherichia coli, unacylated moiety of phosphatidylglycerol from bacteria and mitochondria, and some phosphoglycolipids of lactic acid bacteria, this method may be useful in the structural and metabolic studies of these materials.

Archaea↗

PubMed2000

Progesterone is a cell death suppressor that downregulates Fas expression in rat corpus luteum.

In female rats, apoptotic cell death in the corpus luteum is induced by the prolactin (PRL) surge occurring in the proestrous afternoon during the estrous cycle. We have previously shown that this luteolytic action of PRL is mediated by the Fas/Fas ligand (FasL) system. During pregnancy or pseudopregnancy, apoptosis does not occur in the corpus luteum. Progesterone (P4), a steroid hormone secreted from luteal steroidogenic cells, attenuated PRL-induced apoptosis in cultured luteal cells in a dose-dependent manner. P4 significantly decreased the expression of mRNA of Fas, but not FasL, in cultured luteal cells prepared from both proestrous and mid-pseudopregnant rats. These data indicate that P4 suppresses PRL-induced luteal cell apoptosis via reduction of the expression level of Fas mRNA in the corpus luteum, suggesting that P4 acts as an important factor that can change the sensitivity of corpus luteum to PRL.

Animals↗