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Biomedical subjects

K Shimada

Publications and source records attributed to K Shimada.

At least 1,351 records · Page 75Linked to original sources
PubMed1985

Gas chromatographic determination of m- and p-hydroxyphenytoin in the urine of epileptic patients.

An analytical method for determining phenytoin and its metabolites in the urine of epileptic patients is described. The analysis was performed for the m- and p-isomers of hydroxyphenytoin, the oxidative products of phenytoin, using gas chromatography. As an internal standard, 5-(4-methylphenyl)-5-phenylhydantoin was chosen; the extraction solvent from human urine was ether-chloroform (3:7). Phenytoin and its hydroxy isomers were satisfactorily determined by the modified on-column methylation technique on a 2% OV-17 column using temperature programming from 180 degrees C to 240 degrees C at 5 degrees C/min.

Adult↗
PubMed1985

Molecular structures of mitochondrial-DNA-like sequences in human nuclear DNA.

Two lambda phage clones carrying mitochondrial-DNA-like (mtDNA-like) sequences isolated from a human gene library were named Lm E-1 and Lm C-2, and their DNA structures were characterized. Lm E-1 contains about 0.4 kb DNA homologous to the 5' portion of the mitochondrial 16S ribosomal RNA (rRNA) gene and Lm C-2, a 1.6 kb DNA homologous to the 3' portion of the 12S rRNA gene and to almost all of the 16S rRNA gene. Comparisons of their nucleotide sequences with those of the corresponding regions of the human mtDNA revealed no detectable DNA rearrangement and their homologies to the human mtDNA are 84% and 80%, respectively. There are neither terminal repeats in the nuclear mtDNA-like sequences nor duplications of the nuclear DNAs flanking the mtDNA-like sequences. Evolutionary relationship between these two human nuclear mtDNA-like sequences and the human and bovine mtDNAs is discussed.

Animals↗
PubMed1985

Short and long latency jaw-opening reflex responses elicited by mechanical stimulation in man.

Jaw-opening reflex responses elicited by tapping the chin during maximum clenching in incisal edge-to-edge contact position were studied in 10 healthy subjects. Stimuli were also delivered during weak clenching on a rubber stamp, separating the incisors by approx. 10 mm and protruding the mandible to the edge-to-edge incisor relationship. All four central incisors were stimulated simultaneously. With weak stimuli, there was a short-latency (9.5 ms) digastric response which may have had a disynaptic pathway. Taps of moderate strength produced long-latency (20 ms) responses, and sometimes a short-latency (9.5 ms) component as well. Strong (non-painful) taps produced an even longer-latency digastric response, 30 ms or more following the stimulus with less synchronization than earlier responses. Jaw-jerk reflexes occurred 8.5 ms following the tap, independently of the magnitude of the stimulus. Local anaesthesia of the upper and lower incisors abolished the digastric muscle response. Thus large periodontal afferents may be responsible for the early digastric reflex activity and smaller fibres for later effects. Temporal summation of the reflex response probably occurred when all incisors were stimulated simultaneously.

Adult↗
PubMed1985

Use of a computer in analysis of heart rate and blood pressure response to the Valsalva maneuver.

The relationship between systolic blood pressure (SBP) and R-R interval (RR) in phase II of the Valsalva maneuver was analyzed with the use of a nonlinear relation. The nonlinear relation introduced here includes time derivatives of SBP and RR, and is a natural extension from the linear one which defines the linear baroreflex sensitivity index (BRSI). The model equations of SBP and RR derived from the nonlinear relation predicted well the observed changes of SBP and RR in 11 normotensive subjects and 16 hypertensive patients. Two of the parameters of the relation were related to the activity of the compensatory mechanism, and discriminated well the hypertensives from the normotensives. For this analysis an interactive system of regression analysis has been developed to reduce the difficulties in the case of nonlinear regression curve fitting. The regression curves can be monitored on a graphic terminal during every regression step. The values of nonlinear parameters can be obtained easily and systematically with use of the system.

Adult↗
PubMed1985

Insertion of a long KpnI family member within a mitochondrial-DNA-like sequence present in the human nuclear genome.

Structural analysis of a phage lambda Charon 4A clone carrying one of the human nuclear mitochondrial(mut)-DNA-like sequences revealed that a KpnI-family member (KpnI 5.5-kb DNA) is inserted within this sequence. The inserted KpnI 5.5-kb DNA contains several possible polyadenylation signal sequences followed by an A-rich sequence at its 3' end and is flanked by perfect 13-bp direct repeats of the duplicated mtDNA-like sequences. These structures strongly suggest that the KpnI 5.5-kb DNA is a mobile element. Comparison of the 5' terminal sequences of the KpnI 5.5-kb DNA and four other long KpnI-family DNAs so far examined, using the predicted general promoter sequence for eukaryotic tRNAs, indicates that they contain the consensus sequences for the split internal RNA polymerase III control region.

Base Sequence↗
PubMed1985

Cloning and sequence analysis of a cDNA encoding porcine mitochondrial aspartate aminotransferase precursor.

The primary structure of pig mitochondrial aspartate aminotransferase (mAspATase; L-aspartate:2-oxoglutarate aminotransferase, EC 2.6.1.1) precursor was deduced from its cDNA sequence. A library of cDNA clones was constructed from pig liver poly(A)+ RNA by applying the vector/primer method of Okayama and Berg [Okayama, H. & Berg, P. (1982) Mol. Cell. Biol. 2, 161-170]. The library was screened for pig mAspATase sequences by using a mixture of eight oligodeoxyribonucleotides as a probe. The sequences of the probe were deduced from the known amino acid sequence of pig mAspATase residues 196-201. Two recombinant plasmids containing inserts of about 2500 and 2600 base pairs were selected for sequence analysis. The amino acid sequence predicted from the cDNA sequence shows that the pig mAspATase precursor consists of the mature enzyme of 401 amino acid residues and an amino-terminal segment of 29 amino acid residues called the "presequence" that contains four basic amino acid residues, no acidic residues, and no hydrophobic amino acid stretch. The sequence of this 29-amino acid mAspATase precursor segment was compared with the presequences of other mitochondrial enzymes.

Amino Acid Sequence↗
PubMed1985

Interleukin 2 mRNA induction in human lymphocytes: analysis of the synergistic effect of a phorbol ester and phytohemagglutinin.

Induction of interleukin 2 (IL2) mRNA synthesis in human tonsillar lymphocytes was studied by quantifying the relative levels of IL2 mRNA in the lymphocytes stimulated under various conditions by the dot hybridization method. A remarkable increase of IL2 mRNA was induced by stimulation with phytohemagglutinin (PHA) in the presence of 12-O-tetradecanoyl-phorbol-13-acetate (TPA). The kinetic study revealed that the IL2 mRNA level of the lymphocytes increased from 2 h of culture, reached a maximal level at 12 h, maintained a relatively high level until 48 h and then sharply decreased by 72 h after the stimulation. Inhibition experiments with actinomycin D showed that the increase was due to a transient synthesis of the mRNA after the stimulation, which almost stopped by 12-16 h. DNA synthesis and cell division were not necessary for the induction of IL2 mRNA production but the induction was inhibited by dexamethasone, showing that the production was mainly associated with the G1 phase of the cell cycle. Two-step culture experiments showed that prior exposure of the lymphocytes to TPA for 1 h at 37 degrees C resulted in a remarkable increase of IL2 mRNA on subsequent stimulation with PHA. This suggests that TPA induces certain changes in the biochemical pathway of signal transduction so that the cells can be triggered to express IL2 gene by subsequent stimulation with mitogen.

DNA Replication↗
PubMed1985

Light-harvesting pigment-protein complexes of Rhodopseudomonas sphaeroides forma sp. denitrificans.

The composition of the light-harvesting system of Rhodopseudomonas sphaeroides forma sp. denitrificans was investigated. When chromatophores were solubilized by sodium dodecyl sulfate (SDS) at 0 degrees C and subjected to SDS-polyacrylamide gel electrophoresis (SDS-PAGE), at least two B800-B850 pigment-protein complexes, three B870 pigment-protein complexes, a reaction center (RC) complex and two pigmented bands which contained B800, B850, and B870 were resolved. In the re-electrophoresis, the B870 pigment-protein complexes gave rise to a series of multiple pigmented bands. All of these multiple pigment-protein complexes showed almost the same polypeptide composition and absorption spectrum characteristic of the B870 complex. The apparent molecular weights of these B870 complexes showed a regular interval of about 7,000 indicating that these complexes were oligomers of a subunit. It was also found that a predominant B800-B850 pigment-protein complex could be degraded into a small complex via some intermediates. These results indicate that essentially two kinds of pigment-protein complexes construct the light-harvesting system of this bacteria and, upon treatment with SDS, these complexes are degraded into many classes of subunit aggregates showing a complicated profile of pigmented bands on the gel. Pigmented bands which contained both of B800-B850 and B870 complexes were considered to arise from occasional co-migration of distinct B800-B850 and B870 pigment-protein complexes.

Aerobiosis↗
PubMed1985

Novel structure of the 5' end region of the human argininosuccinate synthetase gene.

The structure of the 5' end region of the human argininosuccinate synthetase (AS) gene was analyzed in detail. The 5' flanking region up to 350 nucleotides from the putative transcription initiation site is unusually G+C rich (80%). Three repeats of a CCGCCC sequence and one complementary GGGCGG sequence are present in this region. It contains no CCAAT box-like sequence, but does contain one typical TATA box and a 20 bases-long inverted repeat sequence that could form a stem and loop structure just upstream from the TATA box. An octanucleotide sequence, AGAAGTGA, found in the 5' flanking region of the AS gene is also commonly present in those regions of the two other human genes expressed mainly in the liver. These structural features of the AS gene indicate that it shares common structures with two completely different groups of genes, i.e. tissue-specific genes and housekeeping ones. Moreover, two enhancer core-like sequences, alternating purine-pyrimidines tracts and two independent Alu type highly repetitive sequences are apparent in the first intron of the AS gene.

Argininosuccinate Synthase↗
PubMed1985

Structural comparisons between mouse and human prealbumin.

In an attempt to construct model systems for familial amyloidotic polyneuropathy, prealbumin cDNA was cloned from a mouse liver cDNA library, using previously cloned human prealbumin cDNA as a hybridization probe. The primary structure of mouse prealbumin deduced from the cDNA sequence shows that it consists of 147 amino acids, including a whole prealbumin sequence (127 amino acids) and a putative signal sequence (20 amino acids). These numbers are in complete agreement with those determined for the human prealbumin. Among the 127 amino acid residues of the mature human prealbumin, 25 are replaced by different amino acids in the mouse prealbumin. Interestingly, 24 out of the 25 substituted amino acids are located at the outer surface of the protein, and the regions corresponding to the core and central channel of the protein are almost completely conserved. The cloned cDNA provided essential information for manipulating amyloidosis in mice.

Amino Acid Sequence↗
PubMed1985

Detection of circulating antigens in sera of rabbits infected with Toxoplasma gondii.

Experiments were performed to investigate the usefulness of an enzyme-linked immunosorbent assay utilizing avidin-biotin interaction as a diagnostic tool for detection of Toxoplasma antigen in blood. The lower limit of sensitivity of the assay by this method was ca. 4 ng/ml, and standard assays provided a linear plot of antigen concentration over a range up to 250 ng/ml. In rabbits inoculated subcutaneously with trophozoites of the RH strain, Toxoplasma antigen became demonstrable in the circulation 3 days after injection, before emergence of antibody in serum and development of parasitemia. Analysis of the antigen in serum from infected rabbits by high-permeation liquid gel chromatography suggested the occurrence of antigens of four different molecular weights, greater than or equal to 400,000, 220,000, 130,000, and 45,000. Of these antigens, those of molecular weights 220,000 and 130,000 showed a conspicuous elevation with time after infection.

Animals↗
PubMed1985

Serological observations of Pneumocystis carinii infection in humans.

Serological examinations of Pneumocystis carinii antigen and antibody were performed in adult patients with P. carinii pneumonia. The antibody titer was assayed by indirect immunofluorescence, and antigenemia was detected by counterimmunoelectrophoresis. Profiles of the time course of antibody levels in serum indicated that development of the antibody occurred at an early stage of pneumonia and that peak titers were obtained during the febrile stage.

Adult↗
PubMed1985

Evidence that cell surface heparan sulfate is involved in the high affinity thrombin binding to cultured porcine aortic endothelial cells.

It has been postulated that thrombin binds to endothelial cells through, at least in part, cell surface glycosaminoglycans such as heparan sulfate, which could serve as antithrombin cofactor on the endothelium. In the present study, we have directly evaluated the binding of 125I-labeled bovine thrombin to cultured porcine aortic endothelial cells. The thrombin binding to the cell surface was rapid, reversible, and displaced by enzymatically inactive diisopropylphosphoryl-thrombin. The concentration of thrombin at half-maximal binding was approximately 20 nM. Both specific and nonspecific binding of 125I-thrombin to the endothelial cell surface was partially inhibited in the presence of protamine sulfate, after the removal of cell surface heparan sulfate by the treatment of cells with crude Flavobacterium heparinum enzyme or purified heparitinase. The binding as a function of the concentration of thrombin revealed that the maximal amount of specific binding was reduced by approximately 50% with little alteration in binding affinity by these enzymatic treatments. The reversibility and active-site independence as well as the rate of the binding did not change after heparitinase treatment. Whereas removal of chondroitin sulfates by chondroitin ABC lyase treatment of cells did not affect the binding, identical enzymatic treatments of [35S]sulfate-labeled cells showed that either heparan sulfate or chondroitin sulfate was selectively and completely removed from the cell surface by heparitinase or chondroitin ABC lyase treatment, respectively. Furthermore, proteolysis of cell surface proteins by the purified glycosaminoglycan lyases was excluded by the identical enzymatic treatments of [3H]leucine-labeled or cell surface radioiodinated cells. Our results provide the first direct evidence that heparan sulfate on the cell surface is involved in the high-affinity, active site-independent thrombin binding by endothelial cells, and also suggest the presence of thrombin-binding sites that are not directly related to heparan sulfate.

Animals↗
PubMed1985

Structure-activity relationship of bufotoxins and related compounds for the inhibition of Na+, K+ -adenosine triphosphatase.

Forty kinds of bufotoxins and related compounds were tested for inhibition of Na+, K+ -adenosine triphosphatase from guinea pig heart, and the structure-activity relationship has been discussed. The inhibitory activities of bufotoxins were dependent upon the dicarboxylic acid and amino acid components. The compounds having both the arginine and suberic acid moieties showed the higher inhibitory activities. The sulfates and glucuronides of cardiac steroids exhibited much less potency than the parent genins. The mode of inhibition was determined by means of the Dixon and Lineweaver-Burk plots.

Animals↗