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Biomedical subjects

H Kotani

Publications and source records attributed to H Kotani.

At least 91 records · Page 5Linked to original sources
PubMed1994

DNA cruciforms facilitate in vitro strand transfer on nucleosomal templates.

A single, phased nucleosome assembled on a 240 bp DNA duplex molecule blocked Escherichia coli RecA protein-promoted strand transfer of the complementary strand of the duplex onto a homologous single-stranded circle. However, when a four-armed cruciform structure was coupled to either end of the duplex the barrier to strand transfer was overcome and joint molecules were efficiently formed. Micrococcal nuclease digestion indicated that the nucleosome was dissociated by the juxtaposition of the cruciform. We interpret these results to mean that cruciform structures can act over a distance to destabilize adjacent nucleosomes and suggest that, as a consequence, the chromatin structure surrounding a crossed strand recombination intermediate might be disrupted, enabling other recombination events to initiate or the process of branch migration to proceed.

Base Sequence↗
PubMed1994

Improved methods of retroviral vector transduction and production for gene therapy.

To facilitate clinical applications of retroviral-mediated human gene transfer, retroviral vectors must be of high titer and free of detectable replication-competent retroviruses. The purpose of this study was to optimize methods of retroviral vector production and transduction. Studies were conducted using 22 retroviral vector producer cell lines. Inactivation of retroviral vectors was greater at 37 degrees C than at 32 degrees C. A 5- to 15-fold increase of vectors was produced at 32 degrees C compared to 37 degrees C; the vector increase at 34 degrees C was intermediate. For example, PA317/G1Na.40 grew to a titer of 1.8 x 10(7) cfu/ml at 32 degrees C, compared to 5.0 x 10(5) cfu/ml at 37 degrees C. The production of retroviral vectors was scalable achieving similar results in flasks, roller bottles, or a CellCube Bioreactor. Retroviral vectors were concentrated 15-24 times with vector recovery ranging from 91 to 96% in a Pellicon tangential flow filtration system. Retroviral supernatants were successfully lyophilized. The combination of glucose or sorbitol with gelatin resulted in recovery rates of 64-83%. In studies on transduction by retroviral vectors, centrifugation of vector supernatants onto target cells significantly increased transduction efficiency as measured by vector titration for G418 resistance, fluorescence-activated cell sorting (FACS), and polymerase chain reaction (PCR) analyses. The combination of the above methods has significantly increased the growth and transduction by this vector system.

3T3 Cells↗
PubMed1994

A physical map of the genome of a unicellular cyanobacterium Synechocystis sp. strain PCC6803.

An accurate physical map of the genome of a cyanobacterium, Synechocystis sp. strain PCC6803, was constructed on the basis of restriction and linking clone analysis. The genome contained 6 recognition sites for AscI, 25 sites for MluI, and 31 sites for SplI, and the entire genome size was estimated to be 3.6 Mb. Sixteen genes or gene clusters, including those involved in the photosynthetic systems, were localized on the physical map of the genome by hybridization. In the course of the above analysis, two extra chromosomal units with approximate sizes of 110 kb and 125 kb were identified.

Chromosome Mapping↗
PubMed1994

Objective evaluation for bite plate therapy in patients with myofascial pain dysfunction syndrome.

An electromyographic study of the masseter and anterior temporal muscles together with questioning patients regarding subjective symptoms was performed on 15 patients with myofascial pain dysfunction (MPD) syndrome prior to and during bite plate therapy. The electromyographic study was evaluated by the slopes of the voltage tension (V/T) curves (calculated as the value of the relative inclination between the integrated electromyram and the biting force). The improvement of subjective symptoms was recognized earlier than the relief of objective symptoms by bite plate therapy. The results confirm that judgement of level of improvement following treatment of MPD syndrome is more appropriate through objective evaluation. Follow-up recording of the voltage tension can be considered to be an objective indicator for patients with MPD syndrome.

Adolescent↗
PubMed1994

Transcription activates RecA-promoted homologous pairing of nucleosomal DNA.

RecA protein catalyzes the homologous pairing of a single-stranded circular DNA and a linear duplex DNA molecule. When the duplex is packaged into chromatin, formation of homologously paired complexes is blocked. We have established a system for studying the RecA-promoted reaction by using a duplex fragment containing a single-phased nucleosome. Under these conditions there is no reaction leading to formation of joint molecule complexes. However, transcription on the chromatin template activates the formation of complexes. Reaction is dependent on RNA synthesis and DNA sequence homology and proceeds regardless of the direction of transcription.

Cell-Free System↗
PubMed1994

A role for RNA synthesis in homologous pairing events.

The relationship between RNA synthesis and homologous pairing in vitro, catalyzed by RecA protein, was examined by using an established strand transfer assay system. When a short DNA duplex is mixed with single-stranded circles, RecA protein promotes the transfer of the minus strand of the duplex onto the complementary region of the plus-strand circle, with the displacement of the plus strand of the duplex. However, if minus-strand RNA is synthesized from the duplex pairing partner, joint molecules containing the RNA transcript, the plus strand of the DNA duplex, and the plus-strand circle are also observed to form. This reaction, which is dependent on RNA polymerase, sequence homology, and RecA protein, produces a joint molecule that can be dissolved by treatment with RNase H but not RNase A. Under these reaction conditions, product molecules form even when the length of shared homology between duplex and circle is reduced to 15 bp.

DNA, Circular↗
PubMed1994

Langerhans cells closely associated with Thy-1-positive dendritic cells in the stratified squamous mucosal epithelium of mice.

An immunohistochemical study was carried out on two types of dendritic immune cells, Langerhans cells and Thy-1-positive cells, in the epithelium of the forestomach of 1-, 2-, 3-, 4- and 8-week-old mice. Investigation focused on how both types of cells were distributed and might interact in the mucosal epithelium. Langerhans cells and Thy-1-positive dendritic cells appeared in mucosal epithelium at 3 weeks of age, while in the epidermis they were first observed just after birth. In contrast with the epidermal Thy-1-positive cells, mucosal Thy-1-positive cells were closely associated with Langerhans cells. Electron microscopy also confirmed that two types of immune cells interact directly in the stratified squamous mucosal epithelium of mice.

Animals↗
PubMed1994

Non-isotopic restriction mapping of cosmid DNA.

A protocol for the non-isotopic restriction mapping of cosmid DNA was developed. After digestion with lambda terminase and partial digestion with restriction enzymes, DNA fragments containing right or left cohesive cos termini were selectively captured by hybridization with biotinylated oligonucleotides, bound to magnetic beads coated with streptavidin and recovered by heating. Recovered DNA fragments containing cos ends were resolved by agarose gel electrophoresis, and fluorescence from the DNA fragments in the ethidium bromide-stained gel was detected with the fluorescent image analyzer, FMBIO. Restriction maps were directly determined from the ladder of the partial digestion products. Two micrograms of cosmid DNA for each partial digestion were sufficient for mapping the restriction enzyme sites. This procedure provides a prototype for other cos sequence-mediated or other specific sequence-mediated DNA isolation technologies and a convenient method for non-isotopic DNA analysis. The rapid physical analysis of cosmid DNA that we present here will contribute to large DNA structural analyses like the human genome project.

Base Sequence↗
PubMed1994

[Zonisamide monotherapy against absence attacks: report of two cases].

We report two cases of absence seizures, in which zonisamide monotherapy was effective. In one case the attacks recurred 6 months after the beginning of zonisamide therapy but ceased again with an increase of the dosage. The EEG prior to treatment showed 3 Hz generalized spike-wave patterns and 3 Hz high voltage slow wave burst in the right occipital area in one case, and 3.5-4 Hz generalized spike-wave patterns and focal spike-wave complexes in the left frontal to central areas in the other. One of the generalized spike-wave patterns were preceded by right occipital delta wave burst in one case, and bilateral occipital sharp-wave complex in the other. It is suggested that zonisamide monotherapy may be effective against absence seizures with focal paroxysmal discharges.

Child↗
PubMed1993

DNA relaxation mediated by Ustilago maydis type I topoisomerase; modulation by chromatin associated proteins.

Ustilago maydis topoisomerase I relaxes superhelical DNA in the absence of any co-factors. The reaction reaches a defined end-point proportional to the amount of enzyme added and an analysis of the reaction by Hill plot transformation indicates that at least two molecules of topoisomerase must interact with the DNA to catalyze relaxation. The addition of purified Ustilago histone H1 reduces the stoichiometric amount of topoisomerase I required by 50%. H1 histone may function to enhance DNA relaxation through a cooperative mechanism. The purified HMG-like protein from Ustilago also enhances DNA relaxation mediated by the topoisomerase. Whereas H1 stimulates topo I-mediated DNA relaxation through a processive mode, the HMG-like protein enhances through a distributive mechanism. Taken together, these results demonstrate that the interaction of chromosomal proteins with topoisomerase can influence DNA topology, and mechanisms are proposed to explain this enhancement.

DNA Topoisomerases, Type I↗
PubMed1993

Gene structure and expression of the MboI restriction--modification system.

The genes from Moraxella bovis encoding the MboI restriction--modification system were cloned and expressed in Escherichia coli. Three open reading frames were found in the sequence containing the genes. These genes, which we named mboA, mboB, and mboC, had the same orientation in the genome. Genes mboA and mboC encoded MboI methyltransferases (named M.MboA and M.MboC) with 294 and 273 amino acid residues, respectively. The mboB gene coded for MboI restriction endonuclease (R.MboI) with 280 amino acid residues. Recombinant E.coli-MBOI, which contained the whole MboI system, overproduced R.MboI. R.MboI activity from E.coli-MBOI was 480-fold that of M.bovis. The amino acid sequences deduced from these genes were compared with those of other restriction--modification systems. The protein sequences of the MboI system had 38-49% homology with those of the DpnII system.

Amino Acid Sequence↗
PubMed1993

Purification and properties of a cruciform DNA binding protein from Ustilago maydis.

A DNA binding protein with an M(r) of 11,000 was purified from Ustilago maydis. Its solubility in acid, amino acid composition, and mobility during gel electrophoresis are reminiscent of properties observed for the high mobility group nonhistone chromosomal proteins. The protein recognizes cruciform DNA made from oligonucleotides and also binds preferentially to a plasmid containing an extruded cruciform.

Base Sequence↗
PubMed1993

An autopsy case of intracranial hemorrhage during tissue plasminogen activator infusion.

We describe an autopsy case of severe intracranial hemorrhage which occurred during the infusion of tissue plasminogen activator (t-PA) for acute myocardial infarction. A 75-year-old man was admitted with substernal chest pain of 3-h duration and electrocardiographic changes consistent with an acute inferior myocardial infarction. Physical examination was unremarkable, except for an initial blood pressure reading of 160/96 mmHg. The patient received 3,000 IU intravenous heparin followed by a 2.4 x 10(6) IU bolus dose of tissue plasminogen activator (t-PA) (Alteplase). This was followed by a drip infusion of 21.6 x 10(6) IU of t-PA over 1 h (total dose 41 mg). Thirty minutes after the infusion of t-PA was initiated, the patient suddenly lost consciousness and began to have violent convulsions, followed by cardiac arrest. Autopsy revealed massive hemorrhage in the bilateral cerebrum and brain stem. To our knowledge, this is the first case of sudden death during t-PA infusion therapy.

Aged↗
PubMed1993

Ureaplasma canigenitalium sp. nov., isolated from dogs.

Ureaplasma strains isolated from dogs (Canis familiaris) were characterized and compared with the type strains of five previously described species of the genus Ureaplasma, Ureaplasma urealyticum (isolated from humans), Ureaplasma diversum (isolated from cattle), Ureaplasma gallorale (isolated from chickens), Ureaplasma cati (isolated from cats), and Ureaplasma felinum (isolated from cats). The canine strains hydrolyzed urea but not arginine or glucose, were membrane bound, lacked a cell wall, passed through 450-nm-pore-size membrane filters, required cholesterol for growth, and formed minute colonies (diameter, 20 to 140 microns) on agar medium. These canine ureaplasma strains have been reported to be members of four serovars. The four serovars of canine strains fell into a single group on the basis of their genomic properties, as determined by DNA-DNA hybridization. On the basis of these findings, we propose that ureaplasmas with these characteristics belong to a new species, Ureaplasma canigenitalium, with strain D6P-C (= ATCC 51252) as the type strain.

Animals↗
PubMed1993

In vitro antibiotic susceptibility testing of different strains of Mycoplasma fermentans isolated from a variety of sources.

The in vitro susceptibilities to antibiotics of 24 strains of Mycoplasma fermentans (isolated from human immunodeficiency virus type 1-infected AIDS patients, non-AIDS patients with acute respiratory disease, and tissue culture) were determined. MICs for 90% of the strains tested (micrograms per milliliter) were obtained for chloramphenicol (1.25), ciprofloxacin (0.078), clindamycin (0.078), doxycycline (0.625), erythromycin (> 10), gentamicin (> 10), levofloxacin (0.078), lincomycin (0.156), streptomycin (> 10), and tetracycline (0.625).

Acquired Immunodeficiency Syndrome↗
PubMed1993

[Lipid peroxide and free radical scavengers in congenital heart disease with pulmonary hypertension].

There is a strong possibility that lipid peroxide (LPO) exerts a great influence on the persistence of pulmonary vascular obstruction (PVO) after radical operation of congenital heart disease with pulmonary hypertension (PH). We investigated the relationship between LOP and PVO, and discussed the effects of scavengers. Fourteen cases of infantile open heart surgery were investigated. LPO, superoxide dismutase SOD and reduced glutathione (GSH) were measured in blood and lung tissue. In the cases of PH group, the levels of lung tissue and plasma LPO showed significantly higher than those of PS group (p < 0.05) before and after radical operation. The levels of Pp/Ps and pulmonary vascular resistance (PVR) of PH cases showed still higher than those of PS group (p < 0.05) even after radical operation. In addition, the levels of plasma and lung tissue SOD, lung tissue GSH of PH cases were lower than those of PG group. These suggest that LPO plays an important role as the cause of PVO before operation and which remains unchanged even after operation. It is to be expected that increase of the free radical scavengers will be effective to suppress the generation of LPO and at last to reduce the level of PVR after operation.

Free Radical Scavengers↗