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Biomedical subjects

Y Kakimoto

Publications and source records attributed to Y Kakimoto.

At least 19 recordsLinked to original sources
PubMed1994

The 3'-untranslated region of mouse myelin basic protein gene increases the amount of mRNA in immortalized mouse oligodendrocytes.

The 3'-untranslated region (UTR) of the myelin basic protein (MBP) mRNA has been found previously to enhance the translational efficiency of the coding region by two-fold in cell-free translational systems. In this study, we transfected eukaryotic expression vectors containing the reporter cDNA for chloramphenicol acetyltransferase (CAT) with or without the mouse MBP cDNA 3'-UTR into cultured cells. CAT activity in the mouse oligodendrocyte cell line, N20.1, transfected with a CAT cDNA containing the MBP 3'-UTR [CAT-MBP 3'-UTR], was twice as high as that of the CAT cDNA without the 3'-UTR; CAT activities for the two constructs were the same in the mouse fibroblast cell line, NIH 3T3. Using reverse transcriptase PCR quantitative analysis, the expression of mRNA was determined. The level of the [CAT-MBP 3'-UTR] mRNA was about ten times higher than CAT mRNA in N20.1 cells but they were the same in NIH 3T3 cells. We conclude that the 3'-UTR of MBP gene increases gene expression at both the mRNA and protein levels in oligodrocyte cell lines, probably through a post-transcriptional mechanism such a message stabilization.

3T3 Cells↗
PubMed1994

Protection by prosaposin against ischemia-induced learning disability and neuronal loss.

Prosaposin, the protein precursor of saposins A, B, C, and D which activate sphingolipid hydrolases, is abundant in several brain regions including the hippocampus. We infused prosaposin continuously for 7 days into the lateral ventricle of gerbils starting 3 hours before 3-min of forebrain ischemia. Using the step-down passive avoidance task, we demonstrated that ischemia-induced learning disability is prevented almost completely by prosaposin infusion. Subsequent light and electron microscopic examinations showed that pyramidal neurons in the CA1 field of the hippocampus as well as synapses within the strata moleculare, lacunosum/radiatum and oriens of the field were significantly more numerous in gerbils infused with prosaposin infusion than in those receiving saline infusion. These findings suggest that prosaposin possesses neurotrotrophic activity to protect hippocampal CA1 neurons from lethal ischemic damage.

Animals↗
PubMed1994

Anticipation in hereditary dentatorubral-pallidoluysian atrophy.

Anticipation refers to the progressively earlier onset and increase in disease severity in successive generations. We studied four families with hereditary dentatorubral-pallidoluysian atrophy (DRPLA), a neurodegenerative disease, and anticipation was present in the mode of inheritance. In subsequent generations DRPLA shows an earlier onset and more severe as well as additional symptoms. Older onset patients suffer from cerebellar ataxia with or without dementia, whereas younger onset patients present as progressive myoclonus epilepsy syndrome, which consists of mental retardation, dementia, and cerebellar ataxia as well as epilepsy and myoclonus. Anticipation with paternal transmission was significantly greater than with maternal transmission.

Adult↗
PubMed1994

Tissue-specific expression of isoaspartyl protein carboxyl methyltransferase gene in rat brain and testis.

Isoaspartyl protein carboxyl methyltransferase (PIMT) is widely distributed in mammalian tissues. Using a polymerase chain reaction-generated 124-bp DNA fragment from brain cDNA as a probe, four different sizes (approximately 4.0, 2.5, 1.7, and 1.1 kb) of transcripts were detected with northern blot analysis. They were expressed predominantly in rat brain and testis. The major transcripts were 2.5 and 1.7 kb in the brain and 2.5 and 1.1 kb in the testis. One of the major transcripts specific to the testis (1.1 kb) was determined to study the structural difference of major transcripts in the two tissues. This testicular cDNA had neither the 5' (94 nucleotides) nor the 3' (594 nucleotides) end of previously reported brain cDNA corresponding to 1.7 kb. The mRNA levels and enzyme activities of different regions and developmental changes were examined in the brain. The mRNA levels and enzyme activities were concomitantly high in cerebral cortex and hippocampus. Although they increased rapidly approximately 30 days after birth in the testis and decreased in aged rats, they increased gradually after birth and remained high during the aging of the brain. Both structural and developmental studies show that the expression of the PIMT gene in brain and testis is regulated in a tissue-specific manner.

Aging↗
PubMed1994

Day-night variation of urine volume in Parkinson's disease.

Studies on the circadian rhythm of urine excretion in healthy men have demonstrated that the maximal urine flow occurs in the early afternoon and the minimal around midnight. In this study, an abnormality in the variation of urine volume was found in parkinsonian patients. Urine samples were collected during daytime (9:00-21:00) and nighttime (21:00-9:00). Fifteen healthy control subjects were examined and found to excrete 60% during the daytime and 40% during the nighttime of the total urine volume. Sixteen parkinsonian patients excreted 43% during the daytime and 57% during the nighttime. In contrast to the control subjects, the parkinsonian patients excreted a smaller volume of their urine during the daytime than during the nighttime. This finding might be related to the degeneration of dopaminergic and/or nondopaminergic neurons in the brain which control urinary excretion.

Adult↗
PubMed1993

Distribution of prosaposin-like immunoreactivity in rat brain.

Prosaposin is the precursor for saposins A, B, C, and D, which are small lysosomal proteins required for the hydrolysis of sphingolipids by specific lysosomal hydrolases. With a monospecific anti-saposin C antibody, which cross-reacts with prosaposin but not with saposin A, B, or D, the present immunoblot experiments showed that the rat brain expresses an unprocessed approximately 72 kDa protein (possibly prosaposin) and little saposin C. Regional analysis demonstrated that prosaposin is abundant in the brainstem, hypothalamus, cerebellum, striatum, and hippocampus, and less abundant in the cerebral cortex. Consistent with this finding, prosaposin-like immunoreactive neurons and fibers as revealed by immunohistochemistry were observed frequently in subcortical regions. The medial septum, diagonal bands, basal nucleus of Meynert, ventral striatum, medial habenular nucleus, and motor nuclei of cranial nerve had significant numbers of immunoreactive neurons. There were also nerve fibers with prosaposin-like immunoreactivity in several projection fields of the above nuclei. Other brain areas that contained prosaposin-like immunoreactive neurons and/or processes were: several brain nuclei (nucleus caudate putamen, globus pallidus, substantia nigra, red nucleus) constituting the so-called extrapyramidal system, reticular thalamic nucleus, entopeduncular nucleus, mammillary nuclei, auditory relay nuclei, cerebellum, sensory cranial nerve nuclei, and the reticular formation. The distribution pattern of prosaposin is apparently different from that of other neuroactive substances so far examined, and thus prosaposin may be involved in novel central events.

Animals↗
PubMed1993

Increase of plasma adrenocorticotrophin and cortisol in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated dogs.

Neuroendocrine abnormality of the hypothalamic-pituitary-adrenal axis was investigated in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated dogs as a model of Parkinson's disease. Blood samples were collected every 4 h for 3-4 days before MPTP treatment, around 2 and 4 weeks after the treatment of MPTP (2.5 mg/kg). Adrenocorticotrophin (ACTH) and cortisol concentrations in plasma were determined by radioimmunoassay. The concentrations of plasma ACTH and cortisol increased by 40% and 60% after MPTP treatment, respectively. Circadian rhythms of neither plasma ACTH nor cortisol concentrations were observed in both MPTP-treated and control dogs. This high hypothalamic-pituitary-adrenal function in MPTP-treated dogs suggests that MPTP may influence the activity of the hypothalamic neurons of the dog.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1992

Disappearance of circadian rhythms in Parkinson's disease model induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in dogs.

Administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to dogs produces clinical, pathological and neurological features in dog resembling human Parkinson's disease. Using this animal model, we studied the changes in diurnal rhythms of urine volume, creatinine in urine, and vasopressin, aldosterone and renin activity in plasma. Before MPTP treatment, urine volume showed a peak between 17.00 and 1.00 and plasma vasopressin concentration also showed a clear circadian rhythm with a peak at 13.00 and a minimum level at 5.00. Two weeks after MPTP treatment (2.5 mg/kg i.v.), the rhythm of urine volume disappeared and that of vasopressin became less clear. Plasma renin activity increased 2 and 4 weeks after MPTP treatment. The increase was, however, not enough to change the concentration of plasma aldosterone. We examined the effect of L-3,4-dihydroxyphenylalanine (levodopa), on the circadian pattern of urine volume and vasopressin attenuated by MPTP. Levodopa (4 mg/kg/day) was administered orally every day from the first week after MPTP treatment. The circadian rhythms of urine volume and vasopressin reappeared within one week after the start of levodopa administration.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1992

Saposin-C from bovine spleen; complete amino acid sequence and relation between the structure and its biological activity.

Saposin-C, a small acidic glycoprotein that can activate glucosylceramide-beta-glucosidase, has been isolated from bovine spleen. The complete amino acid sequence of bovine saposin-C was determined by Edman degradation of the purified protein and its fragmented peptides. It contains 80 amino acids, one carbohydrate chain attached to a single asparagine residue and six cysteine residues in oxidized form. The sequence of bovine saposin-C is 76 and 65% identical with the sequences of saposin-C from human spleen and guinea pig liver, respectively. Hydropathy profiles of the sequence of saposin-C from three species were similar despite the significant residue substitutions. Bovine saposin-C had a stronger effect in stimulating bovine beta-glucosidase compared to human saposin-C. However, the effect of human saposin-C in stimulating human enzyme was stronger than that of bovine saposin-C. The region around residue 35, which is next to the extremely hydrophilic region, seems to be important to produce an interaction with the enzyme.

Amino Acid Sequence↗
PubMed1992

Isolation and identification of methylarginines from bovine brain.

Methylarginines in free form were identified in bovine brain. Three compounds were isolated from the basic aliphatic amino acid fraction of bovine brain with several ion-exchange chromatographies. They showed the same Rf values in paper and thin-layer chromatographies as those of authentic NG-monomethylarginine, NG,NG-dimethylarginine, and NG,N'G-dimethylarginine. The migration distance of the isolated compounds in high-voltage paper electrophoresis and the retention times in ion-exchange HPLC were also identical to those of the above authentic methylarginines. We concluded that these three compounds are the methyl derivatives of arginine described above. The amount of these three compounds isolated from 1,090 g of bovine brain was 0.3 mumol of NG-monomethylarginine, 0.1 mumol of NG,NG-dimethylarginine, and 0.5 mumol of NG,N'G-dimethylarginine. The occurrence of these free methylarginines may have an important role in regulating the signal transduction through the nitric oxide system.

Animals↗
PubMed1992

Distribution of free methylarginines in rat tissues and in the bovine brain.

A sensitive and specific method for determining three forms of methylarginine, i.e., NG-monomethylarginine, NG,NG-dimethylarginine, and NG,N'G-dimethylarginine, in mammalian tissues was developed. After partial purification by ion-exchange chromatography, the methylarginines were derivatized to phenylthiocarbamyl compounds and quantitatively determined using HPLC with a reverse-phase C18 column. In rat organs, the highest concentrations of methylarginines were observed in the spleen. In rat brain, cerebellum and olfactory bulb contained large amounts of NG-monomethylarginine and NG,NG-dimethylarginine. A detailed study of the distribution of methylarginines in the bovine brain was also made, and the concentration of NG,N'G-dimethylarginine was almost the same in all regions. The cerebellar gray matter, hippocampus, and hypothalamus contained large amounts of methylarginines. The distribution of methylarginines seems to parallel the distribution of nitric oxide synthase, which is known to be inhibited by NG-monomethylarginine. This may indicate that methylarginines play some role in controlling nitric oxide synthase activity.

Animals↗
PubMed1992

[A case of reversible encephalopathy caused by tegafur].

A case of reversible encephalopathy induced by tegafur: a masked compound of 5-Fluorouracil, is reported and discussed. A 67-year-old Japanese man suddenly began to show changes in mental status after 4.5 months of administration of tegafur for the peritonitis carcinomatosa. Alternation in consciousness supported by electroencephalographic evidence became apparent. The P100 latency in visual evoked potential was prolonged in both sides, and the conduction velocity in ulnar nerves in both sides was also slow. The patient made significant clinical recovery upon discontinuing tegafur, and the abnormal findings on electroencephalography, visual evoked potential and peripheral nerve conduction velocity also returned to normal. When the patients who are taking tegafur show mental symptoms, early diagnosis from both clinical findings and electrophysiological studies should be performed.

Aged↗
PubMed1991

Isolation and characterization of prosaposin from human milk.

Prosaposin is the precursor protein for saposins, which are small lysosomal proteins required for the hydrolysis of sphingolipids by specific lysosomal hydrolases. Prosaposin, in addition to generating the saposins in the lysosomes, also exists as an unprocessed approximately 70-kDa protein in many tissues and secretory fluids. In this study, we isolated prosaposin from human milk. Milk was fractioned by ammonium sulfate precipitation, then chromatographed with DEAE-Sephacel and G-3000 SW gel permeation-HPLC. A fraction containing prosaposin was finally purified with the anti-saposin C IgG attached affinity column. The protein staining of the purified preparation on SDS-PAGE and the Western blotting showed a single band. The sequence of the initial 10 amino acids from N-terminus of the purified protein was identical to the sequence of prosaposin deduced from cDNA. Although prosaposin itself showed beta-glucosidase activator activity at a slight degree, the activity increased much after trypsin treatment. Western blotting of the trypsin-treated sample confirmed the formation of small saposin-like bands from prosaposin by the action of trypsin.

Amino Acid Sequence↗
PubMed1991

Secretion of sphingolipid hydrolase activator precursor, prosaposin.

Sphingolipid hydrolases are activated by activator proteins or saposins. The precursor protein has been expected from the studies on the cDNA for saposins. Here we demonstrate that prosaposin occurs in various kinds of human secretory fluids such as cerebrospinal fluid, semen, milk, pancreatic juice, and bile. However, mature type saposins were not detected in these fluids. In human milk the amount of prosaposin changed during the lactating period; it became high in concentration within a few days after delivery, decreased during the transitional milk lactating stage, and then increased again toward the mature milk lactating stage. Prosaposin was released from human platelets in response to stimulation by thrombin, but mature saposins were not. From the time course of the release of prosaposin induced by thrombin and from the fact that weak platelet agonists, ADP, epinephrine, and collagen, did not cause the release of prosaposin, prosaposin secretion from platelets seemed to be from lysosome like granules. We postulate that some prosaposin works as a precursor for saposins in the lysosomes and the other serves as an extracellular protein with other specific roles.

Adenosine Diphosphate↗
PubMed1991

Isolation and identification of alpha-(beta-alanyl)hypusine from bovine brain.

A unique dipeptide was isolated from bovine brain using five steps of ion-exchange chromatography. Its acid hydrolysate contained equimolar amounts of beta-alanine and hypusine. The structure of the peptide was elucidated as alpha-(beta-alanyl)hypusine using dansylation technique. About 1 mumol of the compound was isolated from 1090 g of bovine brain.

Animals↗