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Biomedical subjects

A Hata

Publications and source records attributed to A Hata.

At least 109 records · Page 6Linked to original sources
PubMed1992

Electrophysiologic study of dysrhythmias after atrial operations in dogs.

Experiments were conducted with 159 dogs to investigate the mechanism of persistent dysrhythmias clinically encountered after atrial-level operations. Those found after incisions to the internodal pathways (INPs) of the right atrium were analyzed using cardiac mapping in an anesthetized or extracorporeally perfused state. Longitudinal incisions of the posterior INP often allowed inducible sustained atrial flutter, with circus movement of excitation around the right atrium near the tricuspid orfice. Sustained atrial flutter thus produced was modified in cycle length by coexisting division of the middle INP but inhibited by that of the anterior INP. Its incidence increased at chronic stage, with marked cicatricial changes. The disrupted anterior INP markedly prolonged conduction time to the atrioventricular node and A-H interval compared with the other disruptions. Persistent atrioventricular junctional rhythm developed in about 50% of the animals after disruption of all three INPs or anterior and posterior INPs; division of the anterior INP was the common potent factor, although no single blocked INP produced persistent junctional rhythm. Our results support the "summation theory." The incidence of junctional rhythm and hypoxia of the sinoatrial node (flow rate of less than 10 mL.100 g-1.min-1) were markedly enhanced by coexisting blockade of atrial feeding arteries in addition to division of the anterior INP. In conclusion, massive posterior INP disruption is a potent anatomic substrate in producing sustained atrial flutter, middle INP division a modifier, and anterior INP division an inhibitor. Division of the anterior INP is a potent anatomic substrate in producing junctional rhythm, and hypoxia involving the sinoatrial node reacts as its synergic factor.

Animals↗
PubMed1992

Benign acute myositis associated with rotavirus gastroenteritis.

Acute myositis developed concomitantly with gastroenteritis in a 2-year-old girl. She had temporary pain and swelling of the calf muscles and transient marked elevation of serum creatine kinase values. Rotavirus antigen was detected in stool by latex agglutination, and there was seroconversion of complement-fixation antibody to rotavirus.

Acute Disease↗
PubMed1992

Shortening of N1 and P3 latencies in event-related potentials observed coincidentally with clinical improvement during nootropic medication in a demented patient: specific effect of nicergoline.

Event-related potentials, measured eight times in a patient in the early stages of dementia, demonstrated that clinical symptoms, especially loss of motivation, improved coincidentally with a shortening of reaction time, N1 latency, and P3 latency during nicergoline medication among three nootropics prescribed. Such a longitudinal study design was considered to be useful for quantifying and objectively comparing effects of various nootropics noninvasively.

Aged↗
PubMed1991

A novel missense mutation in exon 8 of the ornithine transcarbamylase gene in two unrelated male patients with mild ornithine transcarbamylase deficiency.

We studied two unrelated male probands with mild ornithine transcarbamylase (OTC) (E.C.2.1.3.3) deficiency presenting a similar clinical course. Previous analyses of their liver OTCs also revealed similar properties. To identify the underlying molecular defects, we first cloned the entire coding region of the OTC gene from one proband and found a single base-substitution (C to T) leading to the substitution of tryptophan for arginine at amino acid position 277. Using a genomic amplification technique followed by allele specific oligonucleotide hybridization, we identified the same point mutation in the OTC gene of the other proband. We observed the presence of the mutation among family members in at least three generations, and in one asymptomatic hemizygous sibling in each family.

Alleles↗
PubMed1991

Structural and functional diversities of a family of signal transducing protein kinases, protein kinase C family; two distinct classes of PKC, conventional cPKC and novel nPKC.

Recent molecular cloning and biochemical experiments on the nature of protein kinase C (PKC) have revealed the existence of two distinct classes of phorbol ester (and diacylglycerol) receptor/protein kinase, conventional PKC (cPKC) and novel PKC (nPKC). Each of these classes contains multiple related molecules expressed in tissues and cells in a type-specific manner. Although nPKC does not show the typical PKC activity ascribable to conventional PKCs and thus was neglected in earlier studies, several lines of evidence suggest that nPKCs are involved in a variety of cell responses to physiological stimuli and phorbol esters. It is possible that in some cases nPKC is the major mediator of the so-called PKC-activators, such as phorbol esters, mezerein, and bryostatins. In addition to the clear difference between cPKC and nPKC, functional diversity among conventional PKCs has also been demonstrated; PKC gamma differs in its competence to mediate the signal toward transcriptional activation through TPA-responsive cis-acting elements from cPKC alpha and nPKC epsilon. The differences between cPKC and nPKC and among the individual members of each of these two classes, and their specific pattern of distribution in tissues and cells, provide a rationale by which to explain the specificity and diversity of cellular responses to external stimuli generating DAG and to phorbol esters. The results presented here also provide a means to dissect the complex signaling pathway in cells and to analyze the molecular basis underlying the signal transduction processes mediated by this family of protein kinases.

Animals↗
PubMed1991

[An experimental study on supraventricular dysrhythmias after intracardiac surgery, with special reference to relationship between injury of the internodal tract and atrial flutter].

Dysrhythmias after atrial reparative surgery for TGA or ASD can be lethal. Experiments were made to analyze their mechanism, and to search preventive methods. 1. Acute effects of atrial incisions were studied by epicardial mapping on the right atriums (RA) subjected to various incisions with or without internodal tract (INT) involvement 101 dogs. Atrial rapid pacing was used to induce sustained AF or af. 2. Chronic effects of atrial incisions were studied on longitudinal incisions with (8 dogs) or without (8 dogs) posterior INT (PINT) involvement. Few months later they were subjected to mapping, inducibility of AF, and histologic study of hearts. 3. Mechanism of induced AF was analyzed using reentrant circuit of AF in the longitudinal PINT incision group. At acute stage, conduction delay specific to each freewall incision was observed. AF or af was induced in 70.0% of the longitudinal incision with PINT involvement, but only in 1 dog without PINT. At chronic stage, AF was induced in 5 dogs (62.5%) which included 4 dogs not showed AF at acute stage. Marked chronic changes were histologically showed in injured atrial portion. Reentrant circuit of AF was demonstrated on RA near tricuspid orfice. The PINT kept intact is important to prevent AF.

Adult↗
PubMed1990

Direct detection and automated sequencing of individual alleles after electrophoretic strand separation: identification of a common nonsense mutation in exon 9 of the human lipoprotein lipase gene.

Large-scale screening by direct sequencing of DNA to detect molecular variants remains a laborious endeavor whose difficulty is compounded by heterozygosity. We show that mobility shifts of single-stranded DNA electrophoresed under nondenaturing conditions can be used not only to detect variants (Orita,M. et al., 1989, Genomics, 5, 874-879), but also to separate and sequence directly individual alleles. In this manner, we have identified a common variant of human lipoprotein lipase resulting from a nonsense mutation in exon 9 of the gene. Whether this variant is of functional significance remains to be determined.

Alleles↗
PubMed1990

Missense mutation (Gly----Glu188) of human lipoprotein lipase imparting functional deficiency.

Cloning and sequencing of lipoprotein lipase (LPL) cDNA prepared from the adipose tissue of a patient with classical LPL deficiency revealed a G to A transition at nucleotide 818 in all sequenced clones, leading to the substitution of glutamic acid for glycine at residue 188 of the mature protein. Hybridization of genomic DNA with allele-specific oligonucleotides confirmed that the patient was homozygous for this mutation and revealed that carrier status for this mutation among relatives of the patient was significantly associated with hypertriglyceridemia. Assay of the patient's plasma for immunoreactive enzyme and activity demonstrated the presence of a circulating inactive enzyme protein, the concentration of which was further increased by injection of heparin. The mutant sequence was produced by oligonucleotide-directed mutagenesis, and both normal and mutant sequences were cloned into the expression vector pSVL and transfected into COS-1 cells. The normal sequence led to the in vitro expression of an enzyme that bound to heparin-Sepharose and had a specific catalytic activity similar to that of normal postheparin plasma enzyme. By contrast, the mutant enzyme expressed in vitro was catalytically inactive and displayed a lower affinity for heparin than the normal enzyme. We conclude that this single amino acid substitution leads to the in vivo expression of an inactive enzyme accounting for the manifestations of LPL deficiency noted in the patient.

Adipose Tissue↗
PubMed1990

Properties of a hemolysin related to the thermostable direct hemolysin produced by a Kanagawa phenomenon negative, clinical isolate of Vibrio parahaemolyticus.

A hemolytic toxin (Vp-TRH) produced by a Kanagawa phenomenon negative, clinical isolate of Vibrio parahaemolyticus was further characterized. The purified Vp-TRH showed various biological activities, such as fluid accumulation in rabbit ileal loops, increase of rabbit skin vascular permeability, and cardiotoxicity on cultured myocardial cells, all of which are essentially similar to the activities found with thermostable direct hemolysin (Vp-TDH), a pathogenic toxin produced by Kanagawa phenomenon positive V. parahaemolyticus. Immunological similarities of Vp-TRH not only to Vp-TDH but also to hemolytic toxins produced by Vibrio hollisae and Vibrio cholerae non-O1, both of which are also enteropathogens closely related to V. parahaemolyticus, were demonstrated. The amino acid composition and sequence of N-terminal amino acids of Vp-TRH were determined. These results suggest that Vp-TRH has biological and immunological characters similar to Vp-TDH, although they are distinct molecules.

Amino Acid Sequence↗
PubMed1990

Phenotypic expression of heterozygous lipoprotein lipase deficiency in the extended pedigree of a proband homozygous for a missense mutation.

Familial lipoprotein lipase (LPL) deficiency is a rare genetic disorder accompanied by well-characterized manifestations. The phenotypic expression of heterozygous LPL deficiency has not been so clearly defined. We studied the pedigree of a proband known to be homozygous for a mutation resulting in nonfunctional LPL. Hybridization of DNA from 126 members with allele-specific probes detected 29 carriers of the mutant allele. Adipose tissue LPL activity, measured previously, was reduced by 50% in carriers, but did not reliably distinguish them from noncarriers. Carriers were prone to the expression of a form of familial hypertriglyceridemia characterized by increased plasma triglyceride, VLDL cholesterol and apolipoprotein B, and decreased LDL and HDL cholesterol concentrations. These manifestations were age modulated, with conspicuous differences between carriers and noncarriers observed only after age 40. Several noncarriers exhibited similar lipid abnormalities, but without the inverse relationship between VLDL cholesterol and LDL cholesterol noted among carriers. In addition to age and carrier status, the potentially reversible conditions, obesity, hyperinsulinemia and lipid-raising drug use were contributory. Thus heterozygous lipoprotein lipase deficiency, together with age-related influences, may account for a form of familial hypertriglyceridemia.

Adipose Tissue↗
PubMed1990

Compound heterozygote for lipoprotein lipase deficiency: Ser----Thr244 and transition in 3' splice site of intron 2 (AG----AA) in the lipoprotein lipase gene.

Cloning and sequencing of translated exons and intron-exon boundaries of the lipoprotein lipase gene in a patient of French descent who has the chylomicronemia syndrome revealed that he was a compound heterozygote for two nucleotide substitutions. One (TCC----ACC) leads to an amino acid substitution (Ser----Thr244), while the other alters the 3' splice site of intron 2 (AG----AA). The functional significance of the Thr244 amino acid substitution was established by in vitro expression in cultured mammalian cells.

Amino Acid Sequence↗
PubMed1990

Lipoprotein lipase deficiency resulting from a nonsense mutation in exon 3 of the lipoprotein lipase gene.

In DNA from a male patient of German and Polish ancestry who has lipoprotein lipase deficiency, sequencing of all nine exons and intron-exon boundaries corresponding to the coding region of the lipoprotein lipase gene detected a C----T transition leading to the substitution of a stop signal for the codon that normally determines a glutamine at position 106 of the mature enzyme. Hybridization with allele-specific oligonucleotides at this position established that the patient was homozygous for this mutation. This mutation must lead to the synthesis of a sharply truncated protein, accounting for the enzymatic deficiency noted in the patient.

Base Sequence↗
PubMed1989

Structure of the ornithine transcarbamylase (OTC) gene and DNA diagnosis of OTC deficiency.

Complementary and genomic DNA clones corresponding to human ornithine transcarbamylase (OTC) have been isolated and analyzed. Restriction fragment length polymorphisms (RFCPs) on OTC gene locus were analyzed in Japanese female population. Based on these data, a prenatal diagnosis of OTC deficiency was carried out in a risk family. A C-to-T substitution was found in exon 5 of OTC gene is an another female patient.

DNA↗
PubMed1989

Direct evidence that the kinase activity of protein kinase C is involved in transcriptional activation through a TPA-responsive element.

In order to examine the involvement of protein kinase C (PKC) in the transcriptional activation of genes by TPA (12-0-tetradecanoyl phorbol 13-acetate) we have constructed a series of PKC expression plasmids. Transient expression of an active fragment of PKC in rat fibroblasts resulted in the transcriptional activation of a TRE (TPA-responsive element)-CAT chimeric gene which contains various repetitions of collagenase TREs. These provide the first direct evidence that kinase activity of PKC is involved in TPA-induced transcriptional activation through TRE.

Animals↗
PubMed1989

Tandemly reiterated negative enhancer-like elements regulate transcription of a human gene for the large subunit of calcium-dependent protease.

Calcium-dependent protease (CANP, Calpain) is an intracellular protease involved in essential cellular functions mediated by calcium. To understand the mechanism regulating the expression of CANP at the transcriptional level, we isolated a human gene for the large subunit of mCANP (CANP mL) and analyzed its 5'-region. The transcription initiation sites were mapped to multiple positions (-142 to -103, A of initiation ATG as +1). The upstream region lacks typical promoter elements such as TATA and CAAT boxes and is characterized by its high GC content (-300 to -20, 70% GC content). Functional analyses of the 5'-region by a transient expression assay on HeLa cells revealed that the region (-202 to -80) has a promoter activity. The upstream half of the promoter region (-202 to -130) acts as an upstream promoter element in an orientation-independent manner. Upstream of the promoter region are tandemly reiterated multiple regulatory regions (-2.5k to -690, -690 to -460, -460 to -260, and -260 to -202), each of which negatively regulates the CANP mL gene promoter as well as heterologous promoters in an orientation-independent manner. The presence of a cellular factor(s) mediating the action of these positive (promoter) and negative regulatory elements was suggested by an in vivo competition assay. The negative regulation of transcription mediated by these reiterated cis-acting elements and trans-acting factor(s) may play an essential role in the expression of the CANP mL gene.

Amino Acid Sequence↗
PubMed1989

Primary structure and gene localization of human prolidase.

Complementary DNA clones of prolidase (imidodipeptidase, EC 3.4.13.9) were isolated from human liver and placental cDNA libraries. Two clones named lambda PL21 and lambda PP6 from the liver and placental cDNA libraries, respectively, were analyzed in detail. The first clone, lambda PL21, carried a cDNA insert of 1.7 kilobase pairs and covered all the coding region of human prolidase mRNA. The second clone, lambda PP6, contained a 1.8-kilobase insert with a full-length 3'-untranslated region. Comparison of the amino acid sequence predicted from the nucleotide sequence of the cDNA insert of the two clones with the partial amino acid sequence determined by Edman degradation of peptides derived from human erythrocyte prolidase established that both clones code for human prolidase. The amino terminus of the human mature enzyme is blocked and seems to begin with the sequence X-Ala-Ala-Ala. Presumably no processing occurs at the carboxyl terminus. The mature enzyme is composed of 492 residues, corresponding to Mr 54,305. The sequence of prolidase is unique and not similar to any known protein, except for a significant similarity to regions of F1-ATPase alpha and beta subunits from various sources. The gene has been mapped to the short arm of chromosome 19 (19p13.2). Elucidation of the complete amino acid sequence and the gene location of prolidase should provide the basis for understanding structure-function relationships and also inherited disorders caused by deficiency of this metabolically important enzyme.

Amino Acid Sequence↗