Biomedical subjects

T Hamaguchi

Publications and source records attributed to T Hamaguchi.

At least 19 recordsLinked to original sources

PubMed1996

IL-6 mRNA synthesis by peripheral blood mononuclear cells (PBMC) in patients with chronic renal failure.

We measured levels of IL-6 mRNA in PBMC obtained from patients with chronic renal failure, using polymerase chain reaction (PCR). PBMC were isolated from 45 patients on haemodialysis (HD) at the start of HD. PBMC were also isolated from 35 patients on HD at the end of HD, 23 patients on continuous ambulatory peritoneal dialysis (CAPD), 24 undialysed patients with chronic renal failure (CRF), and 19 healthy controls. Total RNA was extracted from PBMC with RNA zol and reverse transcribed into cDNA. To prepare samples containing identical amounts of beta-actin cDNA, we performed competitive PCR by co-amplifying serial dilutions of mutant templates containing a single point mutation which generated a unique Eco RI site. Next, to measure IL-6 cDNA semiquantitatively in the samples containing identical amounts of beta-actin (100 pg), we performed PCR amplification using 2 fg of the IL-6 mutant template containing a unique Eco RI site. Higher levels of IL-6 mRNA in the PBMC were observed in the HD patients than in the CAPD patients and healthy controls. The levels of IL-6 mRNA in the PBMC at the end of HD were not significantly higher than those at the start of HD. These results suggest that the dialysis session itself did not significantly affect IL-6 mRNA levels in the PBMC, but that chronic stimulation by maintenance HD may be associated with higher levels of IL-6 mRNA observed in HD patients.

Adult↗

PubMed1995

RK-682, a potent inhibitor of tyrosine phosphatase, arrested the mammalian cell cycle progression at G1phase.

A specific inhibitor of protein tyrosine phosphatase (PTPase), RK-682 (3-hexadecanoyl-5-hydroxymethyl-tetronic acid) was isolated from microbial metabolites. In vitro, RK-682 inhibited dephosphorylation activity of CD45 and VHR with IC50 54 and 2.0 microM, respectively. In situ, sodium orthovanadate and RK-682 enhanced the phosphotyrosine level of Ball-1 cells, a human B cell leukemia, but not the phosphoserine/threonine level. The PTPase inhibitors, however, had the different arrest point on the cell cycle progression. Sodium orthovanadate inhibited the cell cycle progression at G2/M boundary phase, on the other hand, RK-682 inhibited the G1/S transition.

Aniline Compounds↗

PubMed1995

Compound heterozygous mutations affecting both hepatic and erythrocyte isozymes of pyruvate kinase.

Novel erythrocyte pyruvate kinase gene defects were found in a patient without a family history of consanguinity. The polymerase chain reaction products of the R-type pyruvate kinase cDNA from the propositus contained two point mutations of Ser80 (TCC)-->Pro (CCC) and Arg490 (CGG)-->Trp (TGG). Allele-specific polymerase chain reaction of the genomic DNA revealed that this patient was a compound heterozygote. The mobilities of the patient's L- and R-type pyruvate kinase by thin-layer polyacrylamide gel electrophoresis were abnormal. The results are consistent with the fact that these mutations are within exons common to the hepatic and erythrocyte isozymes.

Adult↗

PubMed1995

Extracellular phosphorylation of membrane protein modifies theta burst-induced long-term potentiation in CA1 neurons of guinea-pig hippocampal slices.

The involvement of ecto-protein kinase activity in activity-dependent long-term potentiation (LTP) was studied in CA1 neurons of guinea-pig hippocampal slices. Application of 5 microM K-252b, an ecto-protein kinase inhibitor, blocked LTP induced by a theta-burst stimulation (3 bursts composed of 5 pulses at 100 Hz with inter-burst intervals of 200 ms). On the other hand, under 10 microM RK682, an ecto-phosphatase inhibitor, a robust LTP was induced by a weak theta-burst stimulation (3 bursts composed of 3 pulses) which was just at the threshold for the induction of LTP in the control perfusate. These findings suggest that ATP released from presynaptic terminals during the burst stimulation plays an important role in the induction of LTP through phosphorylation of extracellular domains of synaptic membrane proteins, as the substrate for ecto-protein kinase.

Animals↗

PubMed1995

The mechanism of ATP-induced long-term potentiation involves extracellular phosphorylation of membrane proteins in guinea-pig hippocampal CA1 neurons.

The mechanism of ATP-induced long-term potentiation was studied pharmacologically using guinea-pig hippocampal slices. Application of 1-10 microM ATP for 10 min transiently depressed and then slowly augmented the synaptic transmission in CA1 neurons leading to long-term potentiation (LTP). This ATP-induced LTP was blocked by the addition of K-252b, an ecto-protein kinase inhibitor, but was enhanced by the addition of RK682, an ecto-phosphatase inhibitor, both of which do not permeate the cell membrane. These results suggest that ATP applied to the perfusate provides enough substrate for ecto-protein kinase to induce LTP through phosphorylation of extracellular domains of membrane proteins in CA1 neurons.

Adenosine Triphosphate↗

PubMed1995

Phosphofructokinase deficiency: recent advances in molecular biology.

Phosphofructokinase (PFK) plays a major role in glycolysis. Deficiency of PFK-M is characterized by muscle weakness due to fuel crisis in exercising muscles. To elucidate the gene defect of PFK-deficient patients, we have cloned and determined the complete structure and transcription mechanism of human PFK-M mRNA and gene. Molecular defects were investigated in three unrelated Japanese family cases. The first case was characterized by a point mutation at the donor site of intron 15 of the PFK-M gene. Cryptic splicing resulted in a 25 amino acid truncation in the patient's PFK-M. The second case possessed a point mutation at the donor site of intron 19, resulting in the skipping of exon 19 and the truncation of 55 amino acids. In the third case, a missense mutation was identified in the coding region. The review of an updated mutation repertoire indicates the heterogeneity of the molecular mechanism of the disease.

Animals↗

PubMed1995

A new variant case of muscle phosphofructokinase deficiency, coexisting with gastric ulcer, gouty arthritis, and increased hemolysis.

Muscle phosphofructokinase (PFK) deficiency includes both clinically and genetically heterogeneous conditions. A 22-year-old man with muscle PFK deficiency due to previously unrecognized mutation was admitted because of gastric ulcer. He had noticed mild fatigability on vigorous exercise, but had never experienced painful cramps and myoglobinuria. His history included five time relapses of gastric ulcer and gouty arthritis at ages 19 and 21 years. His laboratory data showing impaired muscle glycolysis, increased hemolysis, and myogenic hyperuricemia had aspects in common with those reported for the classic form of this disease, except that lactate concentrations in his blood increased considerably after exercise. The mutant PFK enzyme of this patient, who was demonstrated to have a missense mutation, could exert some catalytic activity that permitted glycolytic flux in vivo, thus leading to the absence of typical myopathic symptoms. The association of relapsing gastric ulcer with muscle PFK deficiency was detected for the first time. There is a possibility that oxygen radical-induced tissue damage resulting from increased hypoxanthine on exertion plays a role in the pathogenesis of ulceration, since the patient is more tolerant to exercise than reported cases with the classic form of muscle PFK deficiency.

Adult↗

PubMed1995

Cutaneous histopathology of Conradi-Hunermann syndrome.

The histopathology of the skin in the ichthyosiform erythroderma associated with classical Conradi-Hunermann syndrome has been rarely described. Skin biopsies from 2 infants with the classical features of Conradi-Hunermann syndrome including ichthyosiform erythroderma contained hyperkeratosis, dilated ostia of pilosebaceous structures, and calcium salts in the stratum corneum detectable with special stains. An unusual feature of one case was dilatation of acrosyringeal structures. We hypothesize that dilatation of acrosyringeal structures is analogous to the plugging noted in pilosebaceous units. Taken together, the ichthyosiform erythroderma of Conradi-Hunermann has a distinctive histologic appearance.

Chondrodysplasia Punctata↗

PubMed1995

Cystic clear cell acanthoma.

An histologically typical clear cell acanthoma was identified forming a cystic structure. The finding of clear cell acanthoma within a cyst is histologically unique.

Epidermal Cyst↗

PubMed1995

Ocular absorption, distribution, and systemic absorption of a novel antiglaucoma medication, prostaglandin derivative, in male white rabbits.

A prostaglandin derivative, (5Z,9 alpha,11 alpha,13E)-9,11-dihydroxyprosta- 5,13-dienoic acid sodium salt (S-1033), that lowers intraocular pressure with little adverse effect, may have clinical value in the treatment of glaucoma. After [14C]S-1033 (0.2% solution) was instilled into the eye of a white rabbit, radioactivity and S-1033 appeared in systemic plasma so rapidly (tmax, 5 min) and S-1033 was eliminated very rapidly with half-lives of 2.8 and 11.0 min at alpha- and beta-phases, respectively. The metabolite, M-1, [1R-[1 alpha,2 beta-(1E),3 alpha,5 alpha]]-3,5-dihydroxy-2-(1- octenyl)-cyclopentanepropanoic acid (tetranor-S-1033), appeared in plasma very rapidly (tmax, 5 min), suggesting that a fast metabolism was a major factor in the rapid elimination of S-1033 from plasma. The values for the ratios of the area under the curve of ocular instillation to intravenous administration for radioactivity and S-1033 were 1.01 and 0.52, respectively, indicating that more than half of the S-1033 instilled was transported into the systemic circulation. To clarify the contributing pathway of the massive and rapid systemic absorption of S-1033 after topical dosing, plasma levels of S-1033 were investigated after instillation to rabbits in which the nasolacrimal ducts were occluded. Plasma concentrations of S-1033 were slightly higher than those in intact rabbits, suggesting that conjunctiva would be as important as nasal mucosae for the systemic absorption under the physiological condition. As for the intraocular distribution, the highest levels of radioactivity were found in the cornea, conjunctiva, and anterior sclera.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗

PubMed1994

Expression of mouse phosphofructokinase-M gene alternative transcripts: evidence for the conserved two-promoter system.

Molecular cloning of the 5' part of mouse phosphofructokinase-M cDNA was performed. In the 46 cDNA clones isolated, there were two classes of 5' untranslated sequences. One had an EcoRI site within its 5' untranslated sequence. This showed 83.0% similarity with human type B mRNA for phosphofructokinase-M. The other lacked an EcoRI site, showing 92.9% similarity with human type C mRNA. Using the reverse-transcription PCR technique, we found that the transcript with an EcoRI site was exclusively expressed in cardiac and skeletal muscles, while that without an EcoRI site was expressed in all the mouse tissues examined. The results suggested that the mouse phosphofructokinase-M gene was transcribed through alternative splicing by the multiple promoters. This transcription mechanism was considered to be evolutionarily conserved. The level of phosphofructokinase-M gene expression in mouse cardiac and skeletal muscles decreased in the ketotic diabetic state. Although the regulatory mechanism and the physiological significance are not fully known, this would indicate that phosphofructokinase-M gene transcripts are affected during the diabetic state.

Animals↗

PubMed1994

A new variant of muscle phosphofructokinase deficiency in a Japanese case with abnormal RNA splicing.

A genetic defect was investigated in a newly diagnosed Japanese case with muscle type phosphofructokinase (PFK-M) deficiency. Polymerase chain reaction (PCR) amplification of patient cDNA revealed an in-frame truncation of 165 bases. This was compatible to the complete deletion of exon 19. The rest of the sequence was identical to that of the normal PFK-M cDNA. Sequencing of PCR amplified genomic DNA of the patient revealed a point mutation from G to A at the 5' donor site of intron 19. This mutation resulted in the skipping of exon 19 in the patient mRNA. Homozygosity of this patient was confirmed by allele specific amplification of the genomic DNA. Donor mutations in intron 15 and intron 5 associated with different splicing errors were previously reported to cause this disease. Thus, the human PFK-M gene mutations are heterogeneous, however, the donor mutations and splicing errors would represent one of the frequent causes of this disease.

Adult↗

PubMed1994

Seborrhoeic dermatitis: treatment with anti-mycotic agents.

In order to elucidate the effectiveness of anti-mycotics in treating seborrhoeic dermatitis, an attempt was made to isolate Malassezia from seborrhoeic lesions of patients of seborrhoeic dermatitis. The results revealed that, in male patients, 46/49 cases were positive for Malassezia furfur on the face and 30/48 cases were positive for M. furfur on the scalp. In female patients, 7/13 cases were positive for M. furfur on the face, and 6/17 cases were positive for M. furfur on the scalp. Anti-mycotic agents were excellent in 50% and good in 31% of the spore-positive cases, yielding an overall efficacy rate of 81%. In contrast, the treatment of the face with vehicle alone showed only one excellent result out of 8 cases. Although clinical improvement was rapid on the side treated with a topical corticosteroid in the half-side-test, numerous fungal elements remained. While the improvement with anti-mycotic agents was slower than that with the corticosteroid, clinical improvement became evident by the third week of administration and fungal elements disappeared.

Adolescent↗

PubMed1994

Effect of taurine and methionine on sarcoplasmic reticular Ca2+ transport and phospholipid methyltransferase activity.

Perfusion of rat hearts with buffer containing 300 microM L-methionine led to a decrease in Ca(2+)-induced Ca2+ release in sarcoplasmic reticulum (SR) but an increase in calcium-independent Ca2+ release from junctional SR. These effects of L-methionine were not altered by exposure of the hearts to high levels of extracellular taurine, but changes in the size of the intracellular taurine pool appear to modulate calcium transport in SR through two mechanisms. First, millimolar concentrations of taurine can directly promote release of calcium from 45Ca(2+)-loaded junctional SR vesicles. Second, taurine serves as an inhibitor of SR phospholipid methyltransferase, an enzyme that appears to be responsible for methionine-mediated loss in Ca(2+)-induced Ca2+ release activity and promotion of Ca(2+)-independent Ca2+ release. The data imply that modulation of the intracellular taurine pool may affect cellular calcium homeostasis and myocardial contractile function. This may be important in development of the cardiomyopathy linked to taurine deficiency.

Animals↗

PubMed1993

Picrotoxin as a potent inducer of rat hepatic cytochrome P450, CYP2B1 and CYP2B2.

The induction by the central stimulant picrotoxin of hepatic drug-metabolizing enzymes was studied in rats. The hepatic content of P450 and the activity of benzphetamine N-demethylation increased gradually after administration of picrotoxin dissolved in drinking water (2 mg/mL), to three-times higher levels than the initial values at the third day of treatment. The increase in benzphetamine N-demethylase activity by picrotoxin was somewhat higher than the increase produced by phenobarbital. Supporting these results, immunoblot analysis showed that CYP2B1 and 2B2 proteins in the liver microsomes were increased by picrotoxin Picrotoxinin and picrotin, which are components of the picrotoxin molecule, had the same ability to induce the hepatic activity of benzphetamine N-demethylation. The liver microsomal activities of testosterone 16 alpha- and 16 beta-hydroxylation were enhanced significantly after treatment with picrotoxinin and picrotin. However, benzo[a]pyrene 3-hydroxylation, aniline 4-hydroxylation, and testosterone hydroxylations at the 2 alpha- and 7 alpha-positions were not increased by picrotoxinin and picrotin treatment. In addition to monooxygenase, significant induction of glutathione S-transferase activity for 1-chloro-2,4-dinitrobenzene and UDP-glucuronyltransferase activity for 4-hydroxybiphenyl and 4-nitrophenol was also observed by pretreatment of picrotoxin. These results clearly indicate that picrotoxin is an inducer of phenobarbital-inducible liver enzymes.

Animals↗

PubMed1993

Evaluation of delta-aminolaevulinic acid in blood of workers exposed to lead.

Exposure-effect and exposure-response relation between exposure to lead and delta-aminolaevulinic acid concentration in blood (ALA-B) were examined in 238 male workers exposed to lead. Concentrations of ALA-B ranged from 26 to 352 micrograms/l and lead concentrations in blood (Pb-B) from 7.1 to 86.0 micrograms/dl. Concentrations of ALA-B correlated closely with concentrations of Pb-B (r = 0.74), and increased ALA-B concentration occurred at Pb-B concentrations of around 30 micrograms/dl. Exposure-response curves indicated that the 50 percentile response doses were roughly 30, 40, and 50 micrograms/dl Pb-B when cut off points of ALA-B were set at 50, 60, and 70 micrograms/l respectively. The sensitivity and specificity of measurements of ALA-B concentrations for health screening were sufficiently high when the health based exposure limits of lead were set at 30-50 micrograms/dl. Moreover, a pronounced increase in ALA-B concentrations occurred when the inhibition rate of erythrocyte ALA dehydratase exceeded 85%. These findings suggest that ALA-B is a useful indicator for assessing the early effects of exposure to lead on haem biosynthesis.

Adult↗

PubMed1993

Effect of a high-fat meal on the bioavailability of phenytoin in a commercial powder with a large particle size.

The effect of a high-fat meal on the bioavailability of free acid phenytoin (DPH) from Hydantol powder with a large particle size (mean particle size, 190 microns) was investigated in four healthy male subjects. The drug was administered as a single oral 5 mg/kg dose of free acid DPH in the fasting state, with a low-fat meal, or with a high-fat meal using a crossover study design. Seven blood samples were collected over a 34-h period following drug administration, and the drug plasma concentrations were determined by GLC. In comparison with the fasting state results, the mean area under the plasma concentration-time curve up to infinity after administration (AUC0-infinity) and the peak plasma concentration (Cmax) of DPH from Hydantol powder significantly increased about 2-fold with the intake of the high-fat meal and about 1.5-fold with the intake of the low-fat meal. The elimination rate constant was not significantly different among the three treatments. The increased bioavailability with the high-fat meal probably resulted from accelerated dissolution of the poorly soluble Hydantol powder due to the stimulation of bile flow or delay of the gastric emptying time caused by the fat intake.

Adult↗

PubMed1993

An alternate nonisotopic technique of PCR-mediated allele-specific oligonucleotide analysis for the detection of a point mutation.

We report a simple protocol for the allele analysis of a point mutation using polymerase chain reaction. Conditions have been determined to use probes prepared for the conventional allele-specific oligonucleotide hybridization method directly. After amplification of the genomic region containing the mutation site, the nested polymerase chain reaction was performed using an allele-specific oligonucleotide probe as one side of the primer. Specificity of the amplification was achieved by decreasing the primer concentration in a two segment thermal cycling pattern. This protocol does not require additional special primers and an allelic mutation can be determined non-isotopically.

Alleles↗