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T Saijo

Publications and source records attributed to T Saijo.

At least 19 recordsLinked to original sources
PubMed1992

Impaired tetramer assembly of variant medium-chain acyl-coenzyme A dehydrogenase with a glutamate or aspartate substitution for lysine 304 causing instability of the protein.

Ninety percent of variant medium-chain acyl-CoA dehydrogenase (MCAD) alleles in patients with MCAD deficiency carry a 985 A-->G transition which causes glutamate substitution for lysine 329 in precursor (p) MCAD (K-304 in mature MCAD). We have used site-directed mutagenesis to produce three variant cDNAs encoding variant pMCAD with glutamate (Kp329E2), aspartate (Kp329D), or arginine (Kp329R) substitution for Kp329. We carried out in vitro expression of cDNAs, and incubated the translation products with isolated rat liver mitochondria. Kp329E was imported into mitochondria and processed into the mature subunit as efficiently as wild-type. Gel filtration analysis of the mitochondria revealed that at 10 min after import, markedly more K304E eluted as a monomer than did wild-type, and the amount of K304E tetramer formed was distinctly less than wild-type at any point up to 60 min after import, indicating that the assembly of K304E is defective. After further incubation, K304E decayed more rapidly than did wild-type, indicating a reduced stability. In similar studies, K304R behaved like the wild-type, while K304D closely resembled K304E, indicating that the presence of a basic residue at 304 is essential for tetramer formation and intramitochondrial stability of mature MCAD.

Acyl-CoA Dehydrogenase↗
PubMed1992

Decrease of pyruvate dehydrogenase phosphatase activity in patients with congenital lactic acidemia.

We developed an assay method for pyruvate dehydrogenase phosphatase activity using [1-14C]pyruvate and measured pyruvate dehydrogenase phosphatase activity in cultured skin fibroblasts from three patients with congenital lactic acidemia due to a defect in activation of the pyruvate dehydrogenase complex. The enzyme activity of their fibroblasts was significantly reduced to 50.7%, 64.6% and 63.1% of that of control fibroblasts. These observations suggest that the defect in activation of the pyruvate dehydrogenase complex in these patients might be due to a reduction in pyruvate dehydrogenase phosphatase activity.

Acidosis, Lactic↗
PubMed1992

Mutation of E1 alpha gene in a female patient with pyruvate dehydrogenase deficiency due to rapid degradation of E1 protein.

A mutation of an insertion of 4 bp in the gene for the alpha subunit of pyruvate dehydrogenase (E1 alpha) was found in a female with pyruvate dehydrogenase deficiency due to the rapid degradation of alpha and beta subunit proteins of pyruvate dehydrogenase. This mutation caused a frameshift that altered the amino acid sequence and created a premature stop codon. This 4-bp insertion has been found in an unrelated female patient with E1 alpha deficiency. It is rare that the same mutation is found in unrelated patients with this rare inborn error of metabolism. Furthermore, short deletions or duplications in the E1 alpha gene of patients with E1 alpha deficiency have been found only in exons 10 and 11. These exons may be hot spots for the mutations by the recombinational processes. This patient was heterozygous for the normal and a mutant allele. However, in most of the cultured skin fibroblasts from this patient, the mutant allele was expressed. These observations suggest that the X chromosome containing the normal allele was predominantly inactivated so that she developed lactic acidaemia and neurological abnormalities despite being heterozygous. The mutant alpha subunit protein failed to form a stable structure of pyruvate dehydrogenase, so that both alpha and beta subunit proteins were degraded rapidly.

Alleles↗
PubMed1991

Screening for disorders of pyruvate metabolism by measuring the ratio of the rates of lactate production and pyruvate decarboxylation in cultured skin fibroblasts.

We assayed the rates of lactate production from [1-14C]pyruvate and decarboxylation of [1-14C]pyruvate in cultured skin fibroblasts from 8 patients with disorders of pyruvate metabolism and 16 control subjects. The disorders of pyruvate metabolism could be more readily detected by measuring the ratio between the rates of lactate production and pyruvate decarboxylation by cultured skin fibroblasts than by measuring either the rate in isolation.

Acidosis, Lactic↗
PubMed1991

Clinical and biochemical findings in parents of children with vitamin D-dependent rickets Type II.

Vitamin D-dependent rickets type II is a rare disease caused by a disorder of the receptor for 1, 25-dihydroxyvitamin D (1, 25(OH)2D). Several parameters of this receptor-effector system were investigated to obtain biochemical information on the presumed heterozygotes of vitamin D-dependent rickets type II in parents of five patients and in their age-matched controls. It was found that the serum concentrations of 1, 25-(OH)2D and 24,25-dihydroxy-vitamin D (24,25(OH)2D), and the ratio of 1,25-(OH)2D/24,25-(OH)2D differed significantly in the parents from those of the patients and the respective control groups. In the parents' cultured skin fibroblasts, the activity of 25-hydroxyvitamin D-24-hydroxylase induced by 10(-8) mol/L 1, 25-(OH)2D3 ranged from 50 to 82% of that of their controls (versus 1-13% of controls for the patients). The binding capacity of the parents' [3H]1, 25-(OH)2D3 to the nucleus was 38-54% of that of their control subjects (versus 7-27% of controls for the patients). The parents' values were thus in a range between those of the patients and the control groups. These findings suggest that, in the parents, a partial impairment of the receptor system for 1, 25-(OH)2D led to an imbalance of vitamin D metabolism, thus confirming that vitamin D-dependent rickets type II is an autosomal recessive inherited disease. Serum concentrations of 1, 25-(OH)2D and 24, 25-(OH)2D may provide useful parameters for detecting heterozygotes of this disease.

24,25-Dihydroxyvitamin D 3↗
PubMed1991

Effects of deoxyadenosine on ribonucleotide reductase in adenosine deaminase-deficient lymphocytes.

To explore the relationship between ribonucleotide reductase and immunodysfunction in adenosine deaminase deficiency, the effects of deoxyadenosine on ribonucleotide reductase in ADA-deficient lymphocytes was investigated. An assay system for ribonucleotide reductase in intact permeabilized lymphocytes was developed to approximate physiological conditions. The activity of cytidine diphosphate (CDP) reductase in resting but not in proliferating lymphocytes in culture was inhibited by 1 to 10 mumol/L deoxyadenosine. The resting cells were protected from the toxicity of 1 mumol/L deoxyadenosine by 5 mmol/L nicotinamide or 30 mumol/L deoxycytidine and from that of 10 mumol/L deoxyadenosine by 30 mumol/L deoxycytidine. These findings suggest that depletion of nicotinamide adenine dinucleotide might be the principal cause of death in resting lymphocytes with ADA deficiency. It is concluded that the mechanism of deoxyadenosine toxicity on non-replicating lymphocytes, which may not be mediated by ribonucleotide reductase inhibition, is closely related to the mechanism of immunodysfunction in patients with ADA deficiency.

Adenosine Deaminase↗
PubMed1991

Therapeutic effect of sodium dichloroacetate on visual and auditory hallucinations in a patient with MELAS.

We report a patient with mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes who experienced visual and auditory hallucinations. His blood and cerebrospinal fluid lactate levels were remarkably elevated. Sodium dichloroacetate was administered orally at doses of 12.5 to 100 mg/kg/day. On normalization of the lactate levels, the hallucinations disappeared.

Acidosis, Lactic↗
PubMed1991

Diagnosis of atlantoaxial subluxation in Morquio's syndrome and spondyloepiphyseal dysplasia congenita.

Compression of the spinal cord due to atlantoaxial subluxation was diagnosed in a patient with Morquio's syndrome and in another with spondyloepiphyseal dysplasia (SED) congenita by cervical radiography and magnetic resonance imaging (MRI). The patient with Morquio's syndrome, a 15 year old boy, had no neurologic symptoms and his somatosensory evoked potential (SSEP) was normal. However, MRI demonstrated spinal cord compression at C1-C2. In contrast, the patient with SED congenita, an 11 year old girl, had neck pain, hyperreflexia and loss of vibration sense in both legs. These findings were explained by the absence of P3 and later waves in SSEP and by compression of the spinal cord observed on MRI. Both SSEP and MRI should be used for evaluating disorders in which atlantoaxial subluxation might be present.

Adolescent↗
PubMed1991

Demonstration of an unstable variant of pyruvate dehydrogenase protein (E1) in cultured fibroblasts from a patient with congenital lactic acidemia.

The deficiency of pyruvate dehydrogenase enzyme complex causes congenital lactic acidemia and devastating neurologic abnormalities in newborns and children. In the majority of cases, the basic defect appears to be in the pyruvate dehydrogenase (E1) component, which consists of two subunits, alpha and beta. Whereas some patients are deficient of a single subunit, in other patients both subunits of E1 are missing. To find out why two proteins were deficient, we investigated the cultured fibroblasts of a female patient who had missing E1-alpha and E1-beta protein bands on Western blot. Radiolabeling-immunoprecipitation studies with 35S-methionine revealed that patient fibroblasts synthesized normal sized precursor E1-alpha and E1-beta proteins, which were presumably transported into mitochondria and processed into normal sized mature proteins. However, pulse-chase analysis showed that alpha- and beta-proteins were degraded rapidly compared to normal. Our findings proved that alpha- and beta-subunits were synthesized and processed normally but failed to form a stable structure for incorporation into the pyruvate dehydrogenase complex.

Cells, Cultured↗
PubMed1991

Hemifacial spasm caused by a spontaneous dissecting aneurysm of the vertebral artery. Case report.

The authors describe the first reported case of dissecting aneurysm presenting with hemifacial spasm. The patient was a 58-year-old woman with left hemifacial spasm of 2 years' duration. Cranial nerve examination was otherwise normal and no other clinical symptoms were observed. Vertebral angiography revealed a fusiform enlargement of the left vertebral artery and contrast medium remaining in the intramural false lumen in the venous phase. Microvascular decompression of the facial nerve with wrapping of the aneurysm resulted in complete relief of the hemifacial spasm.

Aortic Dissection↗
PubMed1991

A unique mutation in the vitamin D receptor gene in three Japanese patients with vitamin D-dependent rickets type II: utility of single-strand conformation polymorphism analysis for heterozygous carrier detection.

Vitamin D-dependent rickets type II is a hereditary disease resulting from a defective vitamin D receptor. In three Japanese patients with vitamin D-dependent rickets type II whose fibroblasts displayed normal cytosol binding and impaired nuclear uptake of 1,25-dihydroxyvitamin D3, western, Southern, and northern analyses failed to disclose any abnormalities in vitamin D3 receptor protein and its gene. Exons 2 and 3 of the vitamin D receptor cDNA, which encode the DNA-binding domain consisting of two zinc fingers, were amplified by PCR and sequenced to identify the specific mutations in the vitamin D receptor gene. In the three patients and one normal control a T-to-C transition was found in the putative initiation codon, while this transition was not observed in another normal control. This finding suggested that an original initiation codon was located at positions 10-12 in the human vitamin D receptor cDNA sequence reported previously. In contrast, a unique G-to-A transition at position 140 in exon 3, resulting in substitution of arginine by glutamine at residue 47, was revealed only in these three patients. The arginine at 47 is located between two zinc fingers and is conserved within all steroid hormone receptors. Therefore, it is highly conceivable that this amino acid substitution is responsible for the defect of the vitamin D receptor in the patients. Single-strand conformation polymorphism analysis of amplified DNA confirmed that all patients were homozygous and that parents from one family were heterozygous carriers for this mutation.

Amino Acid Sequence↗
PubMed1991

[A case with MELAS associated with epilepsia partialis continua].

We report a 14-year-old boy with mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS) who presented repeated episodes of abdominal pain and vomiting since the age of 8 years. In addition, he developed strokelike episodes with myoclonic seizures and transient hemiplegia on three occasions. At the age of 14-1/12-years, he also developed epilepsia partialis continua persisting for 10 days, which was associated with myoclonic seizures synchronized with spike discharges at the right central area. Laboratory examination disclosed increased levels of lactate and pyruvate in serum and CSF and low density areas in the bilateral temporal regions on CT scan. Muscle biopsy showed scattered ragged-red fibers. The enzyme activities (pyruvate dehydrogenase complex, pyruvate carboxylase, phosphoenol pyruvate carboxykinase, and cytochrome c oxidase) and the rates of decarboxylation of [3-14C]pyruvate in cultured skin fibroblasts were within normal ranges.

Acidosis, Lactic↗
PubMed1990

Effect of long-term treatment with massive doses of 1 alpha-hydroxyvitamin D3 on calcium-phosphate balance in patients with vitamin D-dependent rickets type II.

Three patients with vitamin D-dependent rickets type II were given massive doses of 1 alpha-hydroxyvitamin D3 for 29 to 36 months and their calcium-phosphate balance was studied during treatment and one month after cessation of treatment. During treatment fasting hypercalciuria was observed in patient 1 and an increased rate of calcium excretion after calcium loading in patients 1 and 2. In these patients, calcium excretion was parallel with the serum 24,25-dihydroxyvitamin D concentration, which may reflect the level of receptor for 1,25-dihydroxyvitamin D. These findings suggested that the responsiveness to 1,25-dihydroxyvitamin D improved during long-term treatment of these two patients with vitamin D-dependent rickets type II.

Calcium↗
PubMed1990

25-Hydroxyvitamin D-24-hydroxylase in phytohemagglutinin-stimulated lymphocytes: intermediate bioresponse to 1,25-dihydroxyvitamin D3 of cells from parents of patients with vitamin D-dependent rickets type II.

A method for assay of 25-hydroxyvitamin D-24-hydroxylase (24-hydroxylase) activity in phytohemagglutinin (PHA)-stimulated lymphocytes was applied to determine whether vitamin D-dependent rickets type II (VDDR II) is hereditary. In normal lymphocytes incubated with PHA for 3 days, maximal and half-maximal responses of 24-hydroxylase were observed after exposure to 10(-8) mol/L and (1.3 +/- 0.4) x 10(-9) mol/L 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3], respectively. These responses were similar to those of cultured skin fibroblasts. In contrast, after exposure to 10(-8), 10(-7), and 10(-6) mol/L 1,25-(OH)2D3, no 24-hydroxylase activity was detected in cells from patients with VDDR II, and intermediate activity was observed in cells from their parents. These findings indicated the presence of an intracellular receptor-effector system for 1,25-(OH)2D3 in peripheral lymphocytes. Heterozygotes of VDDR II could be identified, and autosomal recessive inheritance of the disease was demonstrated. Detection of heterozygotes of this disease was not possible by assay of inhibition of thymidine incorporation, another marker of the function of 1,25-(OH)2D3 in PHA-stimulated lymphocytes. Therefore, assay of 24-hydroxylase induction reflected the receptor status more closely than assay of inhibition of DNA biosynthesis. The assay of 24-hydroxylase activity in PHA-stimulated lymphocytes described here will be useful for diagnosis of VDDR II and study of families of patients with this disease.

24,25-Dihydroxyvitamin D 3↗
PubMed1989

Inhibitory effects of methyl 7-butyl-4,5,6,7-tetrahydro-3-methylamino-4,6-dioxo-5-propyl- 2H-pyrazolo[3,4-d]pyrimidine-2-carboxylate (AA-2379) on lysosomal enzyme and arachidonic acid release from rat polymorphonuclear leukocytes and its mode of action.

AA-2379 (methyl 7-butyl-4,5,6,7-tetrahydro-3-methylamino-4,6-dioxo-5-propyl- 2H-pyrazolo [3,4-d]pyrimidine-2-carboxylate) has antiinflammatory, analgesic, and antipyretic activities, and inhibits the type III allergic (Arthus) reaction. In the studies reported here, we investigated the effect of AA-2379 on rat polymorphonuclear leukocyte (PMN) functions to clarify the mechanism of the antiinflammatory and antiallergic actions of AA-2379. AA-2379 at 10(-4) M inhibited lysozomal enzyme release. AA-2379 inhibits formyl methionyl-leucyl-phenylalanine (fMLP)- and C5a-induced arachidonic acid release; their 50% inhibitory concentrations were 2.8 x 10(-5) and 3.8 x 10(-5) M, respectively. Because dibutyryl cAMP, a cAMP analogue, and 3-isobutyl-1-methylxanthine, a cAMP phosphodiesterase inhibitor, inhibited fMLP-induced arachidonic acid release, and AA-2379 inhibited cAMP phosphodiesterase and increased cAMP content in PMNs, it is likely that AA-2379 inhibited arachidonic acid release by increasing cAMP content in rat PMNs. Furthermore, from the studies of fMLP-induced arachidonic acid release in Ca free medium it is suggested that AA-2379 inhibits the process which depends on Ca concentration in the medium. These results suggest that the inhibitory effect of AA-2379 on inflammation and allergic reactions such as the Arthus reaction is partly exerted by inhibiting PMN functions such as arachidonic acid and lysozomal enzyme release.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1987

Mechanism of action of an antiallergic agent, amlexanox (AA-673), in inhibiting histamine release from mast cells. Acceleration of cAMP generation and inhibition of phosphodiesterase.

Amlexanox markedly inhibits histamine release from rat mast cells. To clarify the mechanism of this inhibition, we investigated the effect of amlexanox on cAMP content, which, when increased, inhibits histamine release in rat peritoneal mast cells. At concentrations of 10(-8)-10(-6)M, amlexanox or isoproterenol increased the cAMP content of mast cells over that of control cells about 2-fold. When the mast cells were incubated with 10(-8), 10(-7) and 10(-6) M of amlexanox combined with 10(-7) M isoproterenol, the cAMP contents were synergistically increased 15-, 60- and 88-fold, respectively. 3-Isobutyl-1-methylxanthine (IBMX) at 10(-6)-10(-4) M increased the cAMP content 1.7-3.8-fold, and a combination of 10(-4) M IBMX and 10(-7) M isoproterenol synergistically increased the cAMP content 41-fold. A combination of amlexanox and IBMX synergistically increased the cAMP content 19-fold. The increase in cAMP content, when amlexanox and isoproterenol were combined, was transient; it peaked at 0.5 min after the drugs were administered, then decreased to 20-30% of the peak value about 2 min later. Pretreatment of mast cells with amlexanox reduced the effect of the combination of amlexanox and isoproterenol, indicating tachyphylaxis; pretreatment with IBMX had no such effect. The cAMP content of macrophages was also increased by amlexanox, but when combined with isoproterenol or PGE2, the effect was additive. Amlexanox inhibited cAMP phosphodiesterase in rat mast cells; its IC50 value was 1.4 X 10(-5) M, and its inhibitory activity was half that of IBMX.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminopyridines↗