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N Maeda

Publications and source records attributed to N Maeda.

At least 379 records · Page 21Linked to original sources
PubMed1993

Sexual dimorphism in the trigeminal motor neurons innervating the mouse masseter muscle.

The extrafusal and intrafusal muscle fibers in the masseter muscle are innervated by motoneurons in the trigeminal motor nucleus (Mo 5). In the present study, we found that the number of trigeminal motor neurons in the male mouse was significantly larger than that in the female. However, we could not detect any significant difference between male and female mice in the number of sensory neurons in the trigeminal mesencephalic nucleus (Me 5). This is the first report on sexual dimorphism in masticatory motoneurons of mammals.

Animals↗
PubMed1993

A common nuclear factor that binds to the transcriptional control regions of ribosomal protein L5 and 5S rRNA genes.

We have examined the binding of chicken nuclear protein to the promoter regions of chicken ribosomal protein L5 and 5S rRNA genes. A nuclear protein was shown to bind to similar sequences in both promoter regions of the L5 gene (-36 to -21) and the internal control region of 5S rRNA gene (56 to 71). Its molecular mass was estimated to be 34 kDa. Competition gel mobility assay showed that the protein is different from the TATA-box binding protein (TBP). The protein may play a role in a transcriptional coordination of the two genes transcribed by different polymerases, RNA polymerase II and III.

Animals↗
PubMed1993

Targeted modification of the apolipoprotein B gene results in hypobetalipoproteinemia and developmental abnormalities in mice.

Familial hypobetalipoproteinemia is an autosomal codominant disorder resulting in a dramatic reduction in plasma concentrations of apolipoprotein (apo) B, cholesterol, and beta-migrating lipoproteins. A benefit of hypobetalipoproteinemia is that mildly affected individuals may be protected from coronary vascular disease. We have used gene targeting to generate mice with a modified Apob allele. Mice containing this allele display all of the hallmarks of human hypobetalipoproteinemia: they produce a truncated apoB protein, apoB70, and have markedly decreased plasma concentrations of apoB, beta-lipoproteins, and total cholesterol. In addition, the mice manifest several characteristics that are occasionally observed in human hypobetalipoproteinemia, including reduced plasma triglyceride concentrations, fasting chylomicronemia, and reduced high density lipoprotein cholesterol. An unexpected finding is that the modified Apob allele is strongly associated with exencephalus and hydrocephalus. These mice should help increase our understanding of hypobetalipoproteinemia, atherogenesis, and the etiology of exencephalus and hydrocephalus.

Alleles↗
PubMed1993

Comparison of Ins(1,4,5)P3 receptors from rat cerebellum and bovine adrenal cortex.

Ins(1,4,5)P3 receptors in adrenal cortical and cerebellar membranes can be distinguished by their affinities for Ins(1,4,5)P3 as well as the potencies with which heparin and Mg2+ inhibit binding. We have found that the differences in Ins(1,4,5)P3 affinity and heparin inhibition are maintained upon receptor solubilization and purification. In contrast to this, heparin-agarose affinity purification of solubilized cerebellar receptors reduces the potency of Mg2+ inhibition to that in adrenal cortex. These results suggest that Ins(1,4,5)P3 receptors in adrenal cortex are structurally distinct from those in cerebellum. Monoclonal antibodies raised against C- and N-terminal regions of mouse cerebellar Ins(1,4,5)P3 receptors recognize 250-300-kDa proteins in both rat cerebellum and bovine adrenal cortex.

Adrenal Cortex↗
PubMed1993

Immunohistochemical localization of the inositol 1,4,5-trisphosphate receptor in the human nervous system.

A monoclonal antibody raised against the mouse cerebellar inositol trisphosphate receptor was used to study the immunohistochemical localization of this protein in the human central nervous system. As in the brain of rodents, strong immunoreactivity was found in dendrites, axon and cell bodies of Purkinje cells, as well as in nerve endings in the cerebellar and vestibular nuclei. Cerebellar efferent fibres were the only positive structures demonstrated in the brainstem and no immunostaining could be detected in the spinal cord or dorsal root ganglia. By contrast, numerous immunoreactive neurons were present in several telencephalic and diencephalic structures, including the brain cortex, hippocampus, basal ganglia, basal forebrain, amygdala and thalamus. Immunostaining of these brain neurons was weaker than that found in Purkinje cells and was evident in cell bodies and dendrites. Thus, the human brain contains a molecule cross-reacting with the mouse inositol trisphosphate receptor protein that is expressed in a pattern similar to that found in rodents. These findings can be of great importance for understanding the function of this protein in normal brain and its modifications in neuropathological disorders.

Aged↗
PubMed1993

The structure and evolution of the human salivary proline-rich protein gene family.

We present the nucleotide sequences of four members of the six-member human salivary proline-rich protein (PRP) gene family. The four genes are PRB1 and PRB2, which encode basic PRPs, and PRB3 and PRB4, which encode glycosylated PRPs. Each PRB gene is approximately 4.0 kb in length and contains four exons, the third of which is entirely composed of 63-bp tandem repeats and encodes the proline-rich portion of the protein products. Exon 3 contains different numbers of tandem repeats in the different PRB genes. Variation in the numbers of these repeats is also responsible for length variations in different alleles of the PRB genes. We have determined a probable evolutionary history of the human PRP gene family by comparing the nucleotide sequences of the six PRP genes. The present-day six PRP loci probably evolved from a single ancestral gene by four sequential gene duplications, leading to six genes that fall into three subsets, each consisting of two genes. During this evolutionary process, multiple rearrangements and gene conversion occurred mainly in the region from the 3' end of IVS2 and the 3' end of exon 3.

Alleles↗
PubMed1993

Identification of an uncommon haptoglobin type using DNA and protein analysis.

The inherited variations in haptoglobin phenotypes are attributed to the homozygous and heterozygous combinations of three common autosomal alleles: HP*1F, HP*1S and HP*2. HP*1F and HP*1S encode polypeptides that differ by two amino acids at positions 51 and 53. The formation of HP*2 is postulated to have resulted from a breakage and subsequent reunion event at non-homologous positions of two HP*1 alleles. The most common form of HP*2 is HP*2FS in which the 5' end of HP*2 resembles HP*1F and the 3' end resembles HP*1S. Homologous crossing over between HP*2 and either an HP*1F or HP*1S allele in HP*2/HP*1 heterozygotes can change the usual type of HP*2 to three other forms: HP*2SS, HP*2FF or HP*2SF. We describe a nuclear family in which the uncommon genotype HP*2SS is one parent caused initial confusion in assigning genotypes to the rest of the nuclear family. The data demonstrate the need for a cautious approach when deducing haptoglobin genotypes from molecular analysis alone.

Alleles↗
PubMed1993

Effects of HMG-CoA reductase inhibitors on skeletal muscles of rabbits.

This study was undertaken to evaluate the potential of HMG-CoA reductase inhibitors, pravastatin sodium (hereafter abbreviated to pravastatin) and simvastatin, for induction of myopathy and influence on the ubiquinone content of skeletal and cardiac muscles and other tissues in the rabbit. Both drugs were administered orally to New Zealand White rabbits (n = 5) at the dose of 50 mg/kg per day for 14 days. Serum cholesterol levels in the pravastatin- and simvastatin-treated groups were reduced significantly by 47% an 58% on day 14 (P < 0.05), respectively, as compared with the control group, but the difference between the two treatment groups was not significant. In animals of the simvastatin-treated group, abnormal elevations of creatine kinase (CK) and lactate dehydrogenase (LDH) levels were observed, in association with severe lesions in skeletal muscles, but not cardiac muscle. The ubiquinone content in skeletal muscle in this treatment group was not affected, even in the muscles that had severe lesions, whereas that in liver and cardiac muscle was significantly reduced compared with the control group. The results suggest that there is no direct correlation between myopathy and the decrease of ubiquinone content in skeletal muscles. In contrast, the animals in the pravastatin-treated group did not show any changes in CK and LDH levels, ubiquinone content in liver and muscles, or in histopathological features of muscle fibers. The difference between the adverse effects seen with the two drugs could be attributed to physicochemical properties: simvastatin permeates the plasma membrane because of its hydrophobic nature, whereas pravastatin does not, because it is hydrophilic.

Administration, Oral↗
PubMed1993

Intrahypothalamic, but not hippocampal, administration of muscimol suppresses hyperglycemia induced by hippocampal neostigmine in anesthetized rats.

We investigated the effects of intrahypothalamic or hippocampal injection of GABA receptor agonists on hyperglycemia induced by hippocampal neostigmine. Prior to the injection of neostigmine (50 nmol) into the hippocampus (HPC), muscimol (0.01-1 nmol) or baclofen (1 nmol) was injected into the bilateral ventromedial hypothalamus (VMH). Muscimol suppressed the hyperglycemia in a dose-dependent manner, but baclofen affected it only minimally. In contrast, neither hippocampal muscimol (1 or 2.5 nmol) nor baclofen (1 nmol) suppressed the hippocampal neostigmine-dependent hyperglycemia. Intrahypothalamic muscimol (1 nmol) also decreased the changes in hepatic venous plasma glucagon and epinephrine significantly. These results indicate that intrahypothalamic muscimol suppresses hyperglycemia caused by cholinergic neurons originating from the HPC, indicating existence of the location specificity.

Analysis of Variance↗
PubMed1993

Immunosuppressive 30-kDa protein in urine of pregnant women and patients with trophoblastic diseases.

Urine samples obtained from normal pregnant women and patients with trophoblastic diseases contain 30-kDa protein that suppresses phytohemagglutinin-induced T cell proliferation. The immunosuppressive protein was measured by a newly developed radioimmunoassay. The 30-kDa protein was demonstrated in almost all urine samples examined, fluid from hydatid vesicles and chorionic extracts, but not in any serum samples except at low levels in some sera from patients with choriocarcinoma. During pregnancy, the level of urinary 30-kDa protein was higher in the first (1625.5 +/- 1212.0 ng/ml, mean +/- S.D.) and second (1457.4 +/- 1332.4 ng/ml) trimesters than in the third trimester (460.6 +/- 419.0 ng/ml). The urinary 30-kDa protein/hCG ratios in patients with choriocarcinoma (8.3 +/- 10.9) were significantly higher than those in patients with hydatidiform mole (0.67 +/- 1.00, P < 0.01) and in all trimesters than those of normal pregnant women (0.54 +/- 0.44 in first trimester, P < 0.05; 0.63 +/- 0.46 in the second trimester, P < 0.05; 0.24 +/- 0.17 in the third trimester, P < 0.01). There is no significant difference between the ratios in hydatidiform mole and normal pregnancy. These findings and the fast disappearance of the 30-kDa protein from the circulation suggest that the 30-kDa protein plays a part in proliferation of trophoblastic cells in, or their invasion into the host by locally suppressing the immune reaction of the host and that the increase in the urinary 30-kDa protein level, in cases of choriocarcinoma, may be due to the malignant transformation of trophoblastic cells resulting in their rapid invasion.

Female↗
PubMed1993

The complete nucleotide sequence of chicken ribosomal protein L7a gene and the multiple factor binding sites in its 5'-flanking region.

The nucleotide sequence of the gene encoding chicken ribosomal protein L7a was determined. The gene contains eight exons and seven introns, which spread over 3613 nucleotides. The transcription initiation sites were located on four consecutive nucleotides GCCC, which are at the 5' terminus of a short polypyrimidine tract of eight base-pairs flanked by G + C-rich regions. Neither a canonical TATA nor a CAAT box was found in the 5'-flanking region. Instead, a short A + T-rich stretch was found at the position where the TATA box is expected to be. There is an intensive nuclear protein binding motif repeated four times in the region -134 to -50. This motif is common to many ribosomal protein genes and may play an important role in the control of ribosomal protein gene expression.

Amino Acid Sequence↗
PubMed1993

Blocking of human fertilization by carbohydrates.

The zona penetration test and triple stain technique were used to elucidate the blocking effects of carbohydrates on human fertilization and their mechanisms. In the presence of D-mannose or D-fructose (final concentration, 50 mmol/l), sperm penetration through the human zona pellucida was completely blocked. The triple stain technique revealed that D-fructose (50 mmol/l) significantly (P < 0.01) suppressed the acrosome reaction of human spermatozoa, while D-mannose did not show a suppressive effect on the acrosome reaction. These results reinforce our hypothesis proposed previously, that a mandatory step in human fertilization is the binding of a D-mannose-binding constituent of the sperm surface to a D-mannose residue in the sperm receptor site on the zona pellucida. In addition, D-fructose may play an important role as an acrosome stabilizing factor in seminal fluid.

Acrosome↗
PubMed1993

Rheological evaluation of X-ray irradiated blood.

CPD blood, in glass containers and polyvinyl chloride (PVC) bags, was X-irradiated with 50 Gy (n = 4), and then stored for up to 4 weeks. Rheological, hematological and biochemical changes of the red cells during storage were examined. Changes in blood viscosity and various properties of red cells (deformability, shape, hematological indices and concentrations of 2,3-diphosphoglycerate and nucleotides) during storage at 4 degrees C were not altered by the irradiation. The rheological, biochemical and morphological properties of red cells were as well preserved in PVC bags as in glass containers. No abnormal and/or cross-linked proteins in red-cell membranes were induced by the irradiation. Irradiation of PVC bags did not affect the above properties of red cells through any changes in the bag constituents. In conclusion, X-ray irradiation with 50 Gy to CPD blood in PVC bags does not affect the rheological functions of red cells.

Blood↗
PubMed1993

Analysis of immunosuppressive mechanism to cytotoxic T lymphocyte generation in patients with advanced cancer.

In vitro activation of cytotoxic T lymphocytes (CTLs) in peripheral blood mononuclear cells (PBMCs) of patients with advanced cancer is extremely difficult. The proportion of monocytes among PBMCs is high in this type of patient. We investigated monocytosis and the mechanism of suppression of CTL generation and obtained the following findings. 1. The cell fraction ratios of PBMCs were divided into two groups: those with a higher proportion of T cells (Group I), and those with a rapid increase in monocytes and a decrease in T cells (Group II). 2. CTL generation occurred in Group I, but was either extremely low or not observed in Group II. 3. Supernatant from the culture of monocytes obtained from Group II remarkably suppressed CTL generation. 4. Statistical analysis revealed that the cancer recurrence rate over a 2-year period was significantly higher in Group II than in Group I. These findings show that monocytes are associated with the recurrence and worsening of cancer. Furthermore, the monocytes exert this effect by releasing a humoral factor that suppresses CTL activation.

Female↗
PubMed1993

Nerve regeneration occurs in the absence of apolipoprotein E in mice.

The concentration of apolipoprotein E (apoE), a high-affinity ligand for the low-density lipoprotein receptor, increases dramatically in peripheral nerve following injury. This endoneurial apoE is thought to play an important role in the redistribution of lipids from the degenerating axonal and myelin membranes to the regenerating axons and myelin sheaths. The importance of apoE in nerve repair was examined using mutant mice that lack apoE. We show that at 2 and 4 weeks following sciatic nerve crush, regenerating nerves in apoE-deficient mice were morphologically similar to regenerating nerves in control animals, indicating that apoE is not essential for peripheral nerve repair. Moreover, cholesterol synthesis was reduced in regenerating nerves of apoE-deficient mice as much as in regenerating nerves of control animals. These results suggest that the intraneural conservation and reutilization of cholesterol following nerve injury do not require apoE.

Animals↗
PubMed1993

Predominant production of amniotic interleukin-1 alpha in cases with premature rupture of the membranes.

PROBLEM: The physiological significances of the two known subtypes of interleukin-1 (IL-1) in amniotic fluid (AF) were examined by measurements of their concentrations and detection of their location. METHOD: Each IL-1 subtype in AF collected from 61 patients were examined by newly developed enzyme-linked immunosorbent assay with high sensitivity. Placenta and umbilical cord from 17 patients were examined immunohistochemically for localization of IL-1. RESULTS: Different types of IL-1 were predominant in AF; the mean (+/- SE) concentration of IL-1 beta (412.8 +/- 105.4 pg/ml) was significantly higher (P < 0.01) than that of IL-1 alpha (116.4 +/- 26.7 pg/ml) in cases with spontaneous vaginal delivery, whereas the concentration of IL-1 alpha (243.1 +/- 81.4 pg/ml) was significantly higher (P < 0.01) than that of IL-1 beta (139.7 +/- 59.4 pg/ml) in cases with premature rupture of the membranes (PROM) without intrauterine infection. In these cases, immunohistochemical studies revealed the presence of IL-1 alpha in the trophoblastic layer of the placenta and epithelium of the umbilical cord. CONCLUSION: Amniotic IL-1 alpha was detected predominantly in cases with PROM, and it is thought to be produced in placenta and fetal skin keratinocyte.

Adult↗
PubMed1993

Lack of apoA-I is not associated with increased susceptibility to atherosclerosis in mice.

The consequences of the lack of apolipoprotein A-I (apoA-I) were evaluated in mice made to lack apoA-I by gene targeting. Inbred strain 129 mice homozygous for the inactive Apoa1 gene and maintained on regular mouse chow had markedly reduced total cholesterol (26% normal) and high-density lipoprotein (HDL) cholesterol (25% normal) levels in their plasma. Their plasma lipoproteins lacked apoA-I and were reduced in all other apolipoproteins but apoE. ApoE comprises about one third of the protein of HDL particles in homozygotes, whereas it is present in only trace amounts in normal HDL. Despite the reduction of HDL cholesterol, no atherosclerotic lesions were observed in any of the homozygous mice evaluated (up to 15 months of age). After being maintained on an atherogenic diet for 4 weeks, total plasma cholesterol of the homozygous mutants increased by 20 mg/dL, while that of normals increased by 60 mg/dL. Mice with mixed 129 and C57BL/6J genetic backgrounds were fed the atherogenic diet for 20 weeks. A small number of foam cells were found attached to the aortic surface in some of the animals, but the extent and occurrence of these depositions were not related to the apoA-I genotype. Our results demonstrate that a lack of apoA-I does not by itself cause atherosclerosis in mice.

Animals↗