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Biomedical subjects

M Maekawa

Publications and source records attributed to M Maekawa.

At least 145 records · Page 8Linked to original sources
PubMed1994

Premature termination mutations in two patients with deficiency of lactate dehydrogenase H(B) subunit.

Two patients with low lactate dehydrogenase (LD) activity were discovered during healthcare examinations and were found to be homozygous for LD-H (heart) subunit deficiency by electrophoretic isoenzyme analysis of serum and erythrocyte hemolysate. The molecular nature of the genetic mutations was characterized by amplification by the polymerase chain reaction and DNA sequencing. In one case, a single-base substitution (T-->G transversion) at codon 147 of the LD-H(B) gene resulted in a nonsense mutation; in the other case, a deletion of 2 base pairs had occurred at codon 139, resulting in a frameshift translation and premature termination.

Adult↗
PubMed1994

[Reestimation of aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ratio based on JSCC consensus method--changes of criteria for a differential diagnosis of hepatic disorders following the alteration from Karmen method to JSCC method].

We estimated clinical criteria of aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ratio that is measured by the consensus method of JSCC (Japan Society of Clinical Chemistry) for serum AST and ALT. The JSCC consensus method is closely correlated with both IFCC (International Federation of Clinical Chemistry) recommended method without pyridoxal phosphate and Karmen method recommended by the expert panel of liver function tests in Japanese Society of Gastroenterology. The slopes of the regression line is estimated to be 1.00 and 0.87 respectively. We propose that the decision making value of AST/ALT ratio to differentiate several types of liver diseases should be set to 0.87 measured by JSCC consensus method, instead of 1.0 measured by Karmen method.

Alanine Transaminase↗
PubMed1993

Purification of a novel ras GTPase-activating protein from rat brain.

GTPase-activating protein (GAP) and neurofibromin, a gene product of neurofibromatosis type I gene, have been identified as factors that stimulate GTPase activity of ras p21. We have previously suggested the presence of novel GAP activity that is immunologically distinguishable from GAP or neurofibromin in both the cytosolic and the particulate fractions of rat brain (Hattori, S., Maekawa, M., and Nakamura, S. (1992) Oncogene 7, 481-485). We have purified this novel GAP molecule from the cytosolic fraction of rat brain by more than 200,000-fold by five successive column chromatographies with a recovery of 6%. Apparent molecular mass of this molecule was estimated to be 100 kDa (p100GAPras). The same p100GAPras was purified from the particulate fraction after extraction with high salt. The activation of GTPase was observed with normal ras p21 but not with oncogenic ras p21, Rap1B/smg21B, or Ram25K. The dissociation constant of p100GAPras toward ras p21 estimated by competitive inhibition using ras p21 in complex with nonhydrolyzable analog of GTP was two times higher than that of neurofibromin and was lower than that of GAP by 2 orders of magnitude. These results clearly indicate that p100GAPras is a novel ras GAP molecule.

Animals↗
PubMed1993

Purification and molecular cloning of a novel acidic calmodulin binding protein from rat brain.

An acidic protein was identified among the insoluble proteins of a growth cone-enriched fraction, and this protein was purified from the Triton- and high NaCl-insoluble fraction of newborn rat brain using several column chromatographies after solubilization at an alkaline condition. The purified protein showed a Ca(2+)-dependent calmodulin binding activity. This protein showed an anomalous behavior in SDS-polyacrylamide gel electrophoresis as that observed in case of GAP-43 (neuromodulin, F1, pp46, p57, B-50) and MARCKS (p87, p80), namely shifts of apparent molecular weights under different acrylamide concentrations. Its physicochemical characteristics, such as heat stability, acidic isoelectric point, and solubility in a 2.5% perchloric acid solution, also resemble the properties of these proteins. cDNA cloning of this protein showed that the NH2-terminal 50-amino acid sequence was almost identical to CAP-23, a previously reported chicken protein of unknown function. Since the COOH-terminal half-regions of these proteins are less similar, the entire sequences of these proteins have 65% homology (52% identity), suggesting that these proteins belong to a family. Immunoblotting of several tissue extracts using a monoclonal antibody against this protein showed its specific expression in brain.

Amino Acid Sequence↗
PubMed1993

Analysis of a genetic mutation in an electrophoretic variant of the human lactate dehydrogenase-B(H) subunit.

An electrophoretic variant of the lactate dehydrogenase (LDH)-B(H) subunit was discovered in a patient with diabetes mellitus. His LDH activity in serum was slightly lower than normal and the LDH isozyme pattern showed an abnormal migration indicating an LDH-B subunit variant of the fast type. The LDH containing the variant subunit revealed a decreased heat stability. DNA analysis of the variant allele detected a base substitution, an A to G transition, at codon 6 (AAA-->GAA). The mutation resulted in the replacement of a lysine by a glutamic acid (K6E). The change may cause the heat instability and affect the net charge of the variant subunit, resulting in an electrophoretic LDH-B subunit variant of the fast type.

Aged↗
PubMed1993

Detection and characterization of new genetic mutations in individuals heterozygous for lactate dehydrogenase-B(H) deficiency using DNA conformation polymorphism analysis and silver staining.

Human lactate dehydrogenase (LDH)--B(H) mutant genes were analyzed by polymerase chain reaction (PCR) and DNA conformation polymorphism. We used polyacrylamide gradient gel and silver staining procedures for DCP analysis, and observed abnormal migration patterns in individuals heterozygous for the LDH-B deficiency. Subsequent sequence determination of the mutant alleles consistently resulted in detection of three single base substitutions (transversions), viz., a C to A at residue "35" (GCG, Ala-->GAG, Glu), a T to G at residue "172" (TTT, Phe-->GTT, Val), and an A to T at residue "176" (ATG, Met-->TTG, Leu). Furthermore, mismatched PCR or amplification refractory mutation system was developed for the rapid screening and confirmation of these mutations. These amino acid replacements may cause conformational changes in neighboring residues; this probably affects the active site arrangement and results in the loss of enzyme activity.

Amino Acid Sequence↗
PubMed1993

Effects of 5-azacytidine on somatic mutation in a soybean test system.

The mutagenic activity of 5-azacytidine (azaC) was assayed in heterozygous soybean plants (Y11y11), according to the appearance of mutational spots (yellow, dark green and twin) on the leaves. When soybean seeds were treated with azaC at 10-100 micrograms/ml, azaC was found to be significantly mutagenic and to exert heritable effects in the soybean test system. Treatment with azaC increased the frequency of twin spots on the leaves. AzaC would thus appear to cause somatic crossing over as its major effect.

Azacitidine↗
PubMed1993

Dialysis-induced hypoxaemia.

A crossover study to compare the effects of seven different dialysers on blood gas conditions during dialysis using acetate-containing dialysate was carried out at five centres in four countries. A significant decrease in pO2 was noted at both 15 and 60 min after the start of dialysis for all dialysers, with the greatest decrease at 60 min. Filtral caused the greatest reduction and F 60 the least change at both 15 and 60 min. These differences were statistically significant according to the ANOVA multiple-range test for variance. pCO2 also declined by 1.0-2.7 mmHg at 15 min and by 0.7-3.8 mmHg at 60 min. The delta pCO2 was comparable across dialysers and no significant differences were found. Although pH showed no change at 15 min, it was slightly but significantly increased at 60 min across all dialysers compared to predialysis values. There were no statistical differences between dialysers. Calculated blood bicarbonate content significantly decreased at 15 min and recovered at 60 min. Along with the greater decrease in pO2, a larger loss of total CO2 was noted for Filtral. On the other hand F 60 caused the least change in total CO2. This difference may be due to membrane characteristics affecting the diffusion coefficient for O2, CO2, and bicarbonate. Multifactorial mechanisms are likely to be involved, but reflex hypoventilation and an increase in O2 consumption also contributed to hypoxaemia in this study.

Acetates↗
PubMed1993

Multicenter study with recombinant human erythropoietin.

A multicenter study with recombinant human erythropoietin (rh-EPO) was carried out. Of 172 hemodialysis patients with anemia selected for the study from 20 hospitals and clinics, 77 were males and 95 females (mean age 53.9 years). A starting dose of 1,500 U of rh-EPO (Epoetin beta) was administered intravenously at the end of every dialysis session. If the efficacy was not acceptable, the dose was increased to 3,000 U. When the target hematocrit was achieved (30%), the total dose was decreased. The results of the study were excellent relative to those of other multicenter studies with regard to efficacy, safety, and changes in laboratory data. The incidence of hypertension was lower in our study compared with other reports because we used a low initial dose. The efficacy of rh-EPO therapy was determined earlier and more reliably by reticulocytes than by hematocrit or hemoglobin. Prompt iron supplement therapy is recommended with careful observation of serum iron and ferritin.

Anemia↗
PubMed1993

Protective effect of R(-)-1-(benzo[b]thiophen-5-yl)- 2-[2-(N,N-diethylamino)ethoxy]ethanol hydrochloride (T-588), a novel cerebral activator, against experimental cerebral anoxia.

Effects of R(-)-1-(benzo[b]thiophen-5-yl)-2-[2- (N,N-diethylamino)ethoxy]ethanol hydrochloride (T-588) on normobaric hypoxia, histotoxic anoxia by KCN and complete ischemia by decapitation were investigated in mice. T-588 (30-100 mg/kg, p.o.) showed a significant and dose-dependent prolongation of the survival time in all of the models studied. Bifemelane (100-300 mg/kg, p.o.) was also protective against all the models. Tacrine was protective against hypoxia but had no effect on anoxia and ischemia. Imipramine was protective against anoxia, but shortened the survival time of hypoxic mice. It had no effect on ischemia. The anti-hypoxic effect of T-588 was completely inhibited by pretreatment with scopolamine (1 mg/kg, i.p.), while the anti-anoxic effect was partially inhibited. Its effect on the ischemia was not affected by scopolamine. Hypoxia decreased the cerebral contents of ATP, phosphocreatine and glucose and increased the contents of lactate in mice. T-588 had no effect on these changes. Bifemelane prolonged pentobarbital-induced sleeping time in mice with the doses inducing anti-anoxic action, but T-588 did not. These results suggest that the activation of the CNS cholinergic system is involved as one of the mechanisms for the anti-anoxic action of T-588.

Animals↗
PubMed1993

Flow velocity paradoxus and pulsus paradoxus in obstructive sleep apnea syndrome.

Echo-Doppler monitoring was performed simultaneously with two-dimensional and M-mode echocardiography, polysomnography and blood pressure recording in an obstructive sleep apnea patient. Increase in tricuspid flow and decrease of mitral flow velocity was demonstrated during each diastole prior to pulsus paradoxus, while aortic flow velocity decreased with pulsus paradoxus during obstructed breathing during sleep.

Adolescent↗
PubMed1993

EPO test in hemodialysis patients.

It is well known that red blood cell (RBC) and reticulocyte counts increase when anemic hemodialysis patients receive repeated administrations of recombinant human erythropoietin(rh-EPO). However, the early response of reticulocyte has not been reported precisely. In this study, reticulocyte counts and its fractions were observed in 8 maintenance hemodialysis patients after a single intravenous administration of 60 u/Kg of rh-EPO. The peripheral blood cells taken from the patients were stained with auramine 0, which bound to RNA and caused fluorescence. R-1000 (Sysmex, Kobe, Japan) analyzed the reticulocytes and classified the stained cells into three groups by the intensity of fluorescence. The number of highly fluorescent reticulocyte, which was young and large, increased and reached its highest level on day 4 after a single administration of rh-EPO. The reticulocyte counts paralleled these changes, but RBC counts did not change after administrations of rh-EPO. These data suggest that the observation of reticulocytes and its fractions in hemodialysis patients after a single administration of rh-EPO could tell us whether reticulocytes are responsive to rh-EPO or not, and this could be called as EPO test.

Adult↗
PubMed1993

[Evaluation of serum enzyme levels considering biological half lives of enzymes--alteration of lactate dehydrogenase isoenzyme pattern due to computer simulation].

The rapid clearance of certain releasing enzymes from blood stream may modify their usefulness as markers of disease. Serum LD isoenzyme patterns are often quite different from those in the affected tissues. Such differences result from differences in the biological half lives of the individual isoenzyme. In order to reveal such phenomena, we applied the one-compartment model to simulate the time dependent changes in the serum LD isoenzyme patterns as a most simple model. When we simulated leukemic cells as an affected origin, LD isoenzyme patterns obtained at a stage of clinical deterioration or active stage, were characterized by a high proportion of LD-2, LD-3 and LD-4, and resembled those of the original leukemic cells. In general, strong similarities in alterations of LD isoenzyme patterns were obtained between the clinical observed time course and simulated time course. These changes in LD isoenzyme patterns are practically observed in the cases of leukemia, lymphoma, and so on. If the original organs are identical, then it is change of disease stage that is responsible for modification of variable LD isoenzyme patterns. Such phenomena must therefore be noted--in doing so, we shall be able to estimate the origin of enzyme release, disease stage, and prognosis.

Computer Simulation↗
PubMed1993

[Diagnostic clue and genomic analysis of LDH-M subunit deficiency].

Lactate dehydrogenase (LDH) M(A) subunit deficiency was first discovered by urinary discoloration and a discrepancy of laboratory data. Since then, five other families with this disorder have been reported in the Japanese population. The response of pyruvate concentration after forearm ischemic work is specific for LDH-M subunit deficiency. During strenuous exercise ATP production is significantly impaired and muscle tissue is damaged. A genetic study revealed a deletion of 20 base-pairs in exon 6 of the LDH-M gene in four families that were homozygous and one family that was heterozygous for LDH-M subunit deficiency. This mutation results in a frame-shift translation and premature termination. In addition to this mutation, we found a nonsense mutation at codon 328 in exon 7 in an individual heterozygous for LDH-M subunit deficiency, and a deletion of 3 base-pairs, TGT at codon 127 in exon 3 in a proposita who was homozygous and in her parents who were heterozygous for LDH-M subunit deficiency in the fifth family. Therefore, molecular heterogeneities were revealed in genetic mutations of LDH-M subunit deficiency.

Adolescent↗
PubMed1992

Effects of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) on somatic mutation in a soybean test system.

The mutagenic activity of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) was assayed in heterozygous soybean plants (Y11y11), based on the appearance of mutational spots (yellow, dark green and twin) on the leaves. When soybean seeds were treated with IQ at concentrations of 0.01-0.1 microgram/ml, the frequency of mutational spots per leaf increased significantly in proportion to the concentration of IQ. At higher concentrations IQ was toxic. The mutagenicity of IQ was enhanced by pretreatment with the hepatic S9 fraction from Aroclor-induced rats. The numbers of yellow and dark green spots per leaf increased markedly by the treatment with IQ and S9-activated IQ, but the number of twin spots did not increase.

Aroclors↗
PubMed1992

Expression of hepatic microsomal cytochrome P450s as altered by uremia.

The proportions of different hepatic microsomal cytochrome P450s expressed in uremic rats were studied with specific antibodies and with a steroid hydroxylase assay. In male uremic rats, the hepatic levels of P450 2C11, a male-specific form, and 3A2, a male-dominant form, were decreased to about 30% at 5 weeks after the induction of uremia. These changes were paralleled by decreases in the activities of testosterone 2 alpha-, 16 alpha-, and 6 beta-hydroxylation. The level of P450 2A1, abundant in immature rats, was increased 2-fold by uremia and accompanied by an increase in testosterone 7 alpha-hydroxylation activity. The levels of P450 2C6 and 2E1 were not changed by uremia. The levels of male-specific and male-dominant forms such as P450 2C11 and 3A2 are affected by the serum level of testosterone, which was decreased in the male rats with uremia. Therefore, castrated rats were prepared to compare the effects of testosterone on hepatic cytochrome P450s in uremic rats with those in castrated rats. When testosterone was administered to the castrated rats, the decreased levels of both P450 2C11 and 3A2 returned to normal. However, the administration of testosterone to the uremic rats did not prevent the decrease in the levels of these P450s. In female rats, changes in the levels of cytochrome P450s were not as great during uremia as those in male uremic rats. The level of P450 2C12, a female-specific form, was not changed; the level of P450 2A1 was increased by 50%, that of 3A2 which is barely detected in female rats was increased by 60%, and that of 2E1 was increased by 25%. These results suggested that the changes in the hepatic levels of cytochrome P450s were affected by factors other than testosterone in uremic rats.

Animals↗