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Biomedical subjects

K Iinuma

Publications and source records attributed to K Iinuma.

At least 109 records · Page 6Linked to original sources

A novel splicing mutation in propionic acidemia associated with a tetranucleotide direct repeat in the PCCB gene.

Propionic acidemia is an inborn error of organic acid metabolism caused by a deficiency of propionyl Coenzyme A (CoA) carboxylase. cDNAs sequenced from a beta subunit deficient Japanese patient (no. 187) showed an in-frame 57-bp deletion in one allele. Genomic DNA analysis revealed a four-nucleotide deletion of bases 3 to 6 in the 3' intron adjacent to the deleted exon, which disrupted the consensus 5' splice signal and caused exon skipping. This deletion removed one-half of a tetranucleotide direct repeat at the splice junction and presumably resulted from slipped mispairing.

Acyl Coenzyme A↗

[In vivo visualization of neurotransmitter function in the human brain by PET].

Measurement of cerebral blood flow and energy metabolism using PET with 15O and 18F labeled tracers allows quantitative evaluation of cerebral metabolism that can be perturbed in pathological states. Neurotransmission is a new target that is visualized by labeling of substrates of enzymes that are involved in neurotransmitter synthesis or degradation. Neuronal receptors are mapped by introducing the labeled ligands that are specifically bound to the receptors in question. We developed unique tracers that label dopamine D2 or histamine H1 receptors. With other available ligands for the muscarinic cholinergic receptors and [18F] fluorodopa, we started clinical investigations to document the state of neurotransmission in patients with epilepsy, Parkinson's disease and dementia. Using [11C] doxepin we observed an increase of H1 receptors in the epileptic foci that showed decreased glucose metabolic rate at the interictal phase. This phenomenon is compatible with reported increase of mu opiate receptors in the brains of epileptic patients. Brain uptake of FDOPA (Ki), calculated by the graphical plot was found relatively stable with age both in the normal population and dementia patients. However, the striatal Ki of FDOPA of severely demented patients significantly reduced, compared with the normal aged subjects. The correlation analysis between FDOPA Ki and severity of dementia as assessed by mini-mental state examination revealed a significant reduction of Ki associated with the disease progression. Increase in D2 receptor density as assessed by the uptake of YM 09151-2 was observed in cases with reduced FDOPA uptake, which may correspond to the state of supersensitivity of the D2 receptors.

Brain↗

[Brain CT studies in 26 cases of aged patients with Down syndrome].

Computed tomographic images of brains from 26 individuals (10 males and 16 females) with Down syndrome were analysed for roentogenographic measurement. Their ages ranged from 14 to 47 years, the average being 28 years. The results showed that their Sylvian fissure ratio was larger in the aged group. A high incidence of calcification in basal ganglia, choroid plexus and pineal body was noted (85%). An increased Sylvian fissure ratio and a high incidence of intracranial calcification may be practically used as representatives of premature aging. Furthermore, a high incidence of mega cisterna magna implicates that it is worthy of study whether individuals with Down syndrome have a predisposition to underdevelopment of cerebellum.

Adolescent↗

AQ-0145, a newly developed histamine H3 antagonist, decreased seizure susceptibility of electrically induced convulsions in mice.

We studied the effect of AQ-0145, a newly developed histamine H3-receptor antagonist, on electrically induced convulsions in mice. AQ-0145 significantly decreased the durations of each convulsive phase. The anticonvulsant effect of AQ-0145 was antagonized by mepyramine (pyrilamine) and ketotifen, centrally acting histamine H1-receptor antagonists. Thus, the blockade by histamine H1 antagonists of the AQ-0145-induced decrease in seizure susceptibility indicated that histamine released by AQ-0145 from the histaminergic nerve terminals interacts with the histamine H1 receptors of postsynaptic neurons. These findings fully support the hypothesis that the central histaminergic neuronal system is involved in the inhibition of seizures. It is suggested that the neuropharmacological data on histamine H3 ligands may provide clinical candidates for the CNS disorders in which histamine plays important roles in mental and behavioral functions. In this study, it was suggested that AQ-0145 was a new clinical candidate of H3 ligands.

Adamantane↗

Clobenpropit (VUF-9153), a new histamine H3 receptor antagonist, inhibits electrically induced convulsions in mice.

The effect of clobenpropit (VUF-9153), a new histamine H3 receptor antagonist, on electrically induced convulsions was studied in mice. Clobenpropit significantly and dose dependently decreased the duration of each convulsive phase. Its anticonvulsant effects were prevented by pretreatment with (R)-alpha-methylhistamine and imetit (VUF-8325), histamine H3 receptor agonists. These findings suggest that the effect of clobenpropit on electrically induced convulsions is due to an increase in endogenous histamine release in the brain, which is consistent with biochemical results that clobenpropit increased brain histidine decarboxylase activity dose dependently. The anticonvulsive effect of clobenpropit was antagonized by mepyramine, a histamine H1 receptor antagonist, but not by zolantidine, a histamine H2 receptor antagonist, indicating that histamine released by the anticonvulsant effect of clobenpropit interacts with histamine H1 receptors of postsynaptic neurons. The present findings of the effect of clobenpropit on electrically induced convulsions are fully consistent with those of thioperamide as described previously (Yokoyama et al., 1993, Eur. J. Pharmacol. 234, 129), supporting the hypothesis that the central histaminergic neuron system is involved in the inhibition of seizures.

Animals↗

2-Thiazolylethylamine, a selective histamine H1 agonist, decreases seizure susceptibility in mice.

The effects of intracerebroventricular (ICV) administration of histamine and its selective agonists on electrically and pentylenetetrazole-induced convulsions in mice were studied. The ICV administration of histamine decreased seizure susceptibility on electrically and pentylenetetrazole-induced convulsions significantly and dose-dependently. The inhibitory effects of histamine were well antagonized by centrally acting histamine H1 antagonists such as pyrilamine (or mepyramine) and ketotifen, but not by a peripherally acting histamine H1 antagonist, astemizole, or a centrally acting H2 antagonist, zolantidine. The ICV administration of 2-thiazolylethylamine, a selective histamine H1 agonist, also decreased seizure susceptibility, which could be antagonized by centrally acting histamine H1 antagonists, whereas dimaprit, a selective histamine H2 agonist, did not affect seizure susceptibility. These findings strengthened the idea that the central histaminergic neuron system plays an inhibitory role in convulsions.

Animals↗

Possible hereditary Y-chromosome instability.

A 9 year old boy, born to a phenotypically normal, non-consanguineous couple was referred for clinical examination due to radio-ulnar synostosis. We made cytogenetic analyses to investigate the genotype-phenotype correlation. Chromosomal studies on the boy and his father revealed a very small Y chromosome in both cases, probably due to loss of the heterochromatic long arm segment. Repeated cytogenetic analysis of the boy was made, using QFQ, CBG, DA/DAPI and fluorescence in situ hybridization (FISH) methods with DYZ1 and DYZ3 probes. The results showed a likely mosaicism of cell lines with either a small Y or a normal Y found in the boy. The small Y appeared to be composed of double centromeric regions, without the heterochromatic segment of the long arm of the Y chromosome. The father refused re-analysis. These findings indicate an inherent instability of the Y chromosome resulting in a familial small Y. The radio-ulnar synostosis may be associated with excessive Y short arms.

Adult↗

Agar plate method using Lactobacillus plantarum for biotin determination in serum and urine.

An improved agar plate method of biotin bioassay using Lactobacillus plantarum ATCC 8014 and bromocresol purple was established to determine biotin levels in human serum and urine. Samples were treated with 4.5 N H2SO4 to liberate free biotin, autoclaved for 1 h and neutralized by 4.5 N NaOH, then 10 microliters was added to wells in each plate. The biotin levels were measured in 190 serum and 59 urine samples, and the means were 2.7 +/- 0.53 ng/ml and 12.4 +/- 5.56 ng/mg of creatinine, respectively. The intra-assay coefficient varience (CV) were 3.2 (n = 20) and 1.3% (n = 23), respectively. The recovery of biotin added (10 ng/ml) to serum was 110.7%, and to urine was 99.6%. These findings suggest that this assay is sufficiently accurate and reproducible for routine use in the clinical laboratory. The excretion of orally administered biotin was also demonstrated by the method.

Agar↗

Determination of free N-acetylneuraminic acid in human body fluids by high-performance liquid chromatography with fluorimetric detection.

Determinations of both the free and bound form of N-acetyl-neuraminic acid (NANA) in several human body fluids, such as serum, cerebrospinal fluid (CSF), saliva, urine, amniotic fluid, and milk were carried out by HPLC with fluorimetric detection. The method utilized 1,2-diamino-4,5-methylenedioxybenzene dihydrochloride (DMB) as a fluorimetric derivatizing reagent. Free-form NANA was obtained from the body fluids after ultrafiltration with Microcon 10 (YM-10 cellulose membrane, filtration limit M(r) = 10,000, Amicon). The DMB derivative of NANA was separated isocratically by a Nucleosil 5C18 column with a mixture of 0.1 M sodium phosphate buffer (pH 2.0)-methanol (75:25, v/v). A gradient elution system was used for urine analysis. Analysis times were 10-30 min. Recoveries of free NANA by ultrafiltration were satisfactory: 95.66 +/- 1.80% for serum and 97.27 +/- 1.55% for CSF, respectively. The high sensitivity and specificity render this method applicable to all the body fluids tested. Although a physiological role for free NANA has not yet been elucidated, the method presented promises to contribute to the basic understanding of the NANA metabolism.

Adolescent↗

Enhancement of cytotoxicity of doxorubicin by verapamil in the hepatic artery infusion for liver tumors in rats.

BACKGROUND: The calcium channel blocker has been demonstrated to be effective in the accumulation and retention of chemotherapeutic agents in tumor cells. METHODS: The effect of verapamil on cytotoxicity of doxorubicin was investigated in a hepatic artery infusion (HAI) for liver tumors of Walker 256 carcinosarcoma in rats. Doxorubicin was infused by way of a hepatic artery by a bolus injection intra-arterially (IA) (1 mg/kg) and a continuous infusion intra-arterially (CIA) (6 mg/kg/day for 6 days). RESULTS: Doxorubicin increased 90% and 66% in tumor tissue following HAI of verapamil by a bolus and continuous infusion (P < 0.05), respectively. However, no enhancement of the accumulation of doxorubicin in the tumor tissue was found in an intravenous administration of verapamil. The CIA infusion of verapamil with doxorubicin inhibited the tumor growth by 73% in comparison with doxorubicin only (P < 0.05). Verapamil administered intravenously (IV) could not induce this inhibitory effect. The CIA administration of verapamil reduced the serum concentration by 45% (P < 0.001) in comparison with the CIV route. Furthermore, the administration of verapamil did not increase the accumulation of doxorubicin in the normal liver and heart tissues. No enhancement of bone marrow suppression and hepatic biochemical influence by doxorubicin was revealed by the concomitant use of verapamil. CONCLUSIONS: The continuous HAI of verapamil remarkably enhanced the cytotoxicity of HAI with doxorubicin for the treatment of hepatic tumor without aggravating the side effects induced by doxorubicin.

Animals↗

Effect of thioperamide, a histamine H3 receptor antagonist, on electrically induced convulsions in mice.

The effect of thioperamide, a histamine H3 receptor antagonist, on electrically induced convulsions was studied in mice. Thioperamide significantly and dose dependently decreased the duration of each phase of convulsion and raised the electroconvulsive threshold. Its anticonvulsant effects were prevented by pretreatment with (R)-alpha-methylhistamine, a histamine H3 receptor agonist. These findings suggest that the effect of thioperamide on electrically induced convulsions is due to an increase in endogenous histamine release in the brain, an effect mediated by histamine H3 receptors. The anticonvulsant effect of thioperamide was antagonized strongly by mepyramine (or pyrilamine), a centrally acting histamine H1 receptor antagonist, but not by zolantidine, a centrally acting histamine H2 receptor antagonist. Thus, the blockade by mepyramine of the thioperamide-induced decrease in seizure susceptibility indicates that histamine released by thioperamide from the histaminergic nerve terminals interacts with the histamine H1 receptors of postsynaptic neurons. These findings support the hypothesis that the central histaminergic system is involved in the inhibition of seizures.

Animals↗

Diazepam therapy of verbal auditory agnosia.

A 7-year-old girl suffered from a gradual loss of her ability to understand speech. But she had normal hearing and understood various environmental sounds. Brain computerized axial tomography showed normal, but electroencephalogram revealed spike and wave activity from temporal leads, especially on the left side. She was diagnosed as having verbal auditory agnosia. The treatment consisted of diazepam therapy. One year after the onset, her impaired auditory comprehension dramatically improved with the use of diazepam. The dichotic listening test revealed a left ear advantage for both environmental sounds and spoken words. The results seemed to suggest that in this patient the right hemisphere might be functioning as a speech center instead of the left one.

Agnosia↗

Dynamic changes in stress fiber expression in rat uterine vein endothelial cells associated with pregnancy.

En face endothelial preparations of rat uterine vein were stained with rhodamine-phalloidin to investigate the dynamics of stress fiber expression during pregnancy. In prepregnant animals, somewhat plump, spindle-like endothelial cells of the uterine vein had only a few short stress fibers. With the progress of pregnancy, however, many long stress fibers appeared within the elongated endothelial cells. Within 2 hr after delivery, these stress fibers became dramatically decreased in number as the cells reverted from an elongated to a plump shape and returned to the prepregnancy level by 14 days postpartum. The uterine vein showed a significant increase in length during pregnancy and quickly shortened after delivery. Thus, expression of stress fibers in endothelial cells of the uterine vein seems to be related to the tension loaded on this vessel during its elongation in parallel with the marked growth of the uterine body during pregnancy. This study shows that stress fibers are dynamic structures that may serve to maintain endothelial cell integrity during the exertion of tensile stress on the vessel wall.

Actins↗

Quantitative evaluation of electron transport system proteins in mitochondrial encephalomyopathy.

The levels of mitochondrial electron transport system proteins cytochrome c oxidase (COX) and complex III were measured in muscle fibers of patients with mitochondrial encephalomyopathy using quantitative immunoelectron microscopy. In a patient with Leigh's encephalopathy, immunoreactive COX protein was decreased to 20% of the normal mean value in all muscle fibers examined, while the amount of complex III was within the normal range. In a patient with fatal infantile COX deficiency, the level of COX protein was found to be decreased to 27-40% of the normal value in all muscle fibers examined. In patients with mitochondrial myopathy, encephalopathy, lactic acidosis associated with stroke-like episodes (MELAS) and chronic progressive external ophthalmoplegia (CPEO), COX protein levels were decreased to 20% of normal in muscle fibers lacking COX activity. In normal fibers, however, COX protein levels were also normal. The amount of complex III protein was normal in COX-deficient muscle fibers. In two patients, in situ hybridization was performed for detection of mitochondrial mRNA. Mitochondrial mRNAs were found to be abundant in muscle fibers with decreased COX protein, suggesting a defect at the mitochondrial protein-synthesis level in a COX-deficient muscle fiber.

Adult↗