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Biomedical subjects

H Ohmori

Publications and source records attributed to H Ohmori.

At least 271 records · Page 15Linked to original sources
PubMed1987

Nucleotide sequences required for a ColE1-type plasmid to replicate in Escherichia coli cells with or without RNase H.

To elucidate the replication mechanism of a ColE1-type plasmid in RNase H-deficient (rnh-) strains of Escherichia coli, we constructed plasmid derivatives that deleted the whole, or a part, of the 5'-AAAAA-3' sequence (positions -3 to +2) that acts as the origin of replication in vivo and in vitro in the presence of RNase H. The activity of plasmid replication in rnh+ cells was found to be reduced by alterations of the AAAAA sequence. The activity could be restored when the derivatives, retaining the upstream sequence down to -8, regained a sequence containing at least two A residues in the region from -3 to +2. By contrast, replication in rnh- cells was maintained at high levels even when the deletion included the AAAAA sequence and extended up to position -7. The activity in rnh- cells decreased as deletions proceeded to -8 and further up to -17, and was abolished completely by further upward deletions. We concluded that in rnh- cells the plasmid replicates by a mechanism that operates only when RNase H is inactive. This RNase H-sensitive replication in rnh- cells seems to require the RNA-DNA hybrid formation that is also required for RNase H-dependent replication in rnh+ cells. The hybrid formation probably contributes by unwinding a portion of DNA from which replication can be initiated.

Base Sequence↗
PubMed1987

beta-Cyclodextrin as a substitute for fetal calf serum in the primary antibody response in vitro.

Fetal calf serum (FCS) must be present at 10% in the culture medium for optimally eliciting the primary antibody response to sheep erythrocytes (SRBC) in murine lymphocytes. The response was no longer observed when FCS was reduced to less than 1%. However, we found that the addition of 250-500 micrograms/ml beta-cyclodextrin (beta-CD) to RPMI 1640 medium containing 1% FCS restored the immune response to a level comparable to that observed in 10% FCS-containing medium. beta-CD did not further augment the response in the presence of 10% FCS. The order of effectiveness of various cyclodextrin compounds tested was as follows: beta-CD (100) greater than alpha-CD(30) greater than gamma-CD(10) greater than heptakis (2,6-O-dimethyl)beta-CD (less than 1). The in vitro antibody response varied drastically depending on the lot of FCS added to the culture medium. The important observation was that even a deficient lot of FCS could elicit the antibody response as efficiently as a good lot if it was added to the culture medium at 1% in combination with beta-CD. beta-CD was also effective in inducing the primary antibody responses to both SRBC and dinitrophenylated Ficoll in serum-free RPMI 1640 medium containing bovine serum albumin, insulin and transferrin. In serum-free conditions, the responses were 40-50% of those in serum-containing medium. beta-CD did not increase the number of antibody-forming cells nonspecifically, nor did it show a significant mitogenic activity and cytotoxicity. These data suggest that beta-CD is a useful material as a serum substitute in inducing primary antibody response in vitro.

Animals↗
PubMed1987

Intravesical chemotherapy.

A total of 85 cases treated by intravesical administration of adriamycin (ADM) at Okayama University and other cooperating institutions were examined. Instillation of 50 mg adriamycin dissolved in 30 ml physiological saline was performed in two courses of 3 consecutive days, with a 4-day interval between the courses. The response rate was 70.6%. Following instillation therapy transurethral resection (TUR) was carried out in 69 cases (80%), segmental cystectomy in 7, and total cystectomy in 3. The follow-up period averaged 42 months, during which the recurrence rate was 57%; recurrence occurred within 18 months in 80% of these cases. Since the recurrence per patient-month x 100 was 3.348, the precise effect of intravesical chemotherapy in the prevention of recurrence was unclear. There were 9 cases of advanced disease (11% of the total, 18% of cases with recurrence). One patient with CIS (flat invasive tumor) seemingly achieved CR, but died 43 months after treatment due to metastatic disease. While this method is not always indicated in cases of CIS (flat invasive tumor), in cases in which it is indicated a drug causing only limited stimulation of the bladder mucosa should be used and long-term follow-up is essential.

Administration, Intravesical↗
PubMed1987

Prophylactic intravesical instillation therapy with adriamycin and mitomycin C in patients with superficial bladder cancer.

Intravesical instillation of adriamycin (ADM) or mitomycin C (MMC) was carried out for the purpose of preventing the recurrence of superficial bladder cancers (Ta and T1) after transurethral resection or transurethral coagulation. First, eligible patients were divided into two groups (solitary and multiple) and then they were randomized into the following three groups: (1) ADM group, intravesical instillation with 50 mg ADM dissolved in 100 ml physiological saline; (2) MMC group, intravesical instillation with 30 mg MMC dissolved in 100 ml physiological saline; (3) control, transurethral resection or transurethral coagulation alone. The drugs were given six times by instillation within 2 weeks after TUR or TUC; after 2 weeks the drugs were administered for 2 consecutive days every 4 weeks for 2 years. Of the 134 patients admitted to the study, 103 were evaluable and 31 were eliminated as non-evaluable patients. The cumulative nonrecurrence rates were 73.6% for ADM, 63.4% for MMC, and 22.5% for controls after a follow-up of 24 months. The cumulative non recurrence rates of the ADM and MMC groups were significantly higher than that of the control group. The incidence of side effects was low and the grade of these side effects mild. This instillation therapy with ADM and MMC was considered useful for preventing the recurrence of superficial bladder cancers.

Administration, Intravesical↗
PubMed1987

Acetylcholine dose-response relation and the effect of cesium ions in the rat adrenal chromaffin cell under voltage clamp.

Acetylcholine(ACh)-induced inward current was examined in the rat adrenal chromaffin cell in culture. Cells were voltage clamped with one electrode using the giga-seal technique. The ACh dose-response relationship was determined by applying various concentrations of ACh with the "puffer" method. Although there were several technical difficulties, we found tentative figures as 135 to 480 microM for the dissociation constant and 1.2 to 1.4 for the Hill coefficient. External Cs ions had a depressing effect on the ACh response. Cs ions may slowly block ACh receptor channels from outside at the resting state. The ACh response in normal saline recorded with the Cs-filled electrode reversed the polarity at -7.1 mV. When the amplitude of ACh-induced current was plotted against holding membrane potential the curve showed strong rectification at the region more negative than the reversal potential. Between +10 and +30 mV there was a region of a negative slope. We discussed possible mechanisms for this characteristic I-V curve.

Acetylcholine↗
PubMed1987

Gating properties of the mechano-electrical transducer channel in the dissociated vestibular hair cell of the chick.

1. The gating property of a mechano-electrical transduction (m-e.t.) was studied in dissociated chick vestibular hair cells having hair bundles of varying length (from 7 to more than 30 microns long). The whole-cell recording voltage-clamp technique was used to record m-e.t. currents, and mechanical stimuli were applied to the hair bundle with a rigid glass rod. 2. Displacements of the glass rod and the hair bundle were measured with a resolution of 0.1 micron from contrast-enhanced television images. The motion of the hair bundle was tightly coupled to the motion of the stimulating glass rod, and displacements were not detected in the circumference of the cell body. Thus, all the displacement applied to the hair bundle resulted in bending about the insertion into the cuticle and relative to the cell body. 3. Displacements of the hair bundle towards the taller stereocilia generated inward-going m-e.t. currents at negative membrane potentials, while displacements of the hair bundle towards the shorter stereocilia generated outward-going m-e.t. currents. These outward going m-e.t. currents reflect closing of the m-e.t. channels which are open at the resting position of the hair bundle. The fraction of these channels open at the resting position was 0.12 +/- 0.04 (n = 7). 4. The displacement-response relationship measured both at -50 mV and at +38 mV were superimposable after scaling. Thus, no voltage dependence was observed in gating of the m-e.t. conductance. 5. When a hair bundle of a shorter length (less than 7.5 microns long) was stimulated at 5 micron form the insertion to the cuticle, the minimum hair-bundle displacement which could generate a detectable amount of m-e.t. current was 0.01 micron. The transduction current was linearly related to the hair-bundle displacement for values of up to 0.6 micron towards the taller stereocilia, and showed saturation with larger displacements. 6. When a hair bundle of a longer length (more than 12.5 microns long) was stimulated (towards the taller stereocilia) at 10 micron from the insertion to the cuticle the m-e.t. current generated was linear for displacements of up to 1.5 micron, and saturated with larger displacements. 7. The above two points suggest that the range of linear transduction becomes wider as the length of the hair bundle becomes longer under in situ conditions where the displacement is likely to be applied at the tip of the hair bundle.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1987

Requirement of the Escherichia coli dnaA gene function for ori-2-dependent mini-F plasmid replication.

The mini-F plasmids pSC138, pKP1013, and pKV513 were unable to transform Escherichia coli cells with a dnaA-defective mutation under nonpermissive conditions. The dnaA defect was suppressed for host chromosome replication either by the simultaneous presence of the rnh-199 (amber) mutation or by prophage P2 sig5 integrated at the attP2II locus on the chromosome, both providing new origins for replication independent of dnaA function. The dnaA mutations tested were dnaA17, dnaA5, and dnaA46. dnaA5 and dnaA46 are missense mutations. dnaA17 is an amber mutation whose activity is controlled by the temperature-sensitive amber suppressor supF6. Under permissive conditions in which active DnaA protein was available, the mini-F plasmids efficiently transformed the cells. However, the transformants lost the plasmid as the cells multiplied under conditions in which DnaA protein was inactivated or its synthesis was arrested. As controls, plasmids pSC101 and pBR322 were examined along with mini-F; pSC101 behaved in the same manner as mini-F, showing complete dependence on dnaA for stable maintenance, whereas pBR322 was indifferent to the dnaA defect. Thus, ori-2-dependent mini-F plasmid replication seems to require active dnaA gene function. This notion was strengthened by the results of deletion analysis which revealed that integrity of at least one of the two DnaA boxes present as a tandem repeat in ori-2 was required for the origin activity of mini-F replication.

Bacterial Proteins↗
PubMed1987

The use of beta-cyclodextrin in lymphocyte culture. Induction of the primary antibody response in vitro in calf serum- or newborn bovine serum-containing culture medium.

In order to induce the primary antibody response to sheep erythrocytes in vitro in murine lymphocytes, the cells are usually cultured in RPMI-1640 medium containing 10% fetal calf serum (FCS). When FCS was replaced by calf serum (CS) or newborn bovine serum (NBS), the antibody response was poor compared with that obtained with FCS. However, a comparable response was induced when CS or NBS was added at 1% to the culture medium in combination with 500 micrograms/ml beta-cyclodextrin (beta-CD). In the presence of beta-CD, the response was the highest when CS or NBS was added at 1%. An important observation was that all the lots of CS (5 lots) and NBS (2 lots) tested supported the response equally in the presence of beta-CD. The anti-sheep erythrocytes response induced by 1% CS or NBS in the presence of beta-CD was shown to be completely dependent on the added antigen, suggesting that beta-CD is not a polyclonal activator. beta-CD showed neither mitogenic nor cytotoxic effects on murine lymphocytes. These results indicate that beta-CD is a useful additive for inducing the primary antibody response in vitro in the culture medium containing CS or NBS which is usually less supportive but less expensive than FCS.

Animals↗
PubMed1987

The use of beta-cyclodextrin-containing culture medium for in vitro evaluation of immunomodulating agents.

We have devised a new culture medium that is made of RPMI-1640 medium, 500 micrograms/ml beta-cyclodextrin (beta-CD) and 1% fetal calf serum (FCS) (beta-CD medium). Murine lymphocytes stimulated with sheep erythrocytes in vitro developed antibody-forming cells in beta-CD medium as efficiently as in 10% FCS-containing RPMI-1640 medium (10F medium). Immunostimulating agents (SA96 and levamisole) and immunosuppressive agents (hydrocortisone and D-penicillamine) showed similar immunomodulating effects on the antibody responses in both media. In addition, the enhancing effect of levamisole varied drastically depending on the lot of FCS used in 10F medium, but a clear enhancement was always observed in beta-CD medium containing any lot of FCS tested.

Adjuvants, Immunologic↗
PubMed1987

[Intravesical chemotherapy with interferon in superficial bladder tumors].

Interferon (IFN) was used in the treatment of superficial bladder tumors. Interferon (IFN-beta, IFN-gamma) was instilled into the bladder at dosages ranging from 16 billion to 36 billion U IFN per 30 ml physiological saline. The IFN was instilled into the bladder once a day or twice a day for 10 to 20 days. In this trial, ten patients with superficial bladder tumors were treated at Okayama City Hospital, and of these, 1 CR, 3 PR, 2 MR and 4 NC were obtained. There were no signs of either irritable bladder or general side effects. IFN (especially IFN-beta) is considered a useful drug for superficial bladder tumors in intravesical chemotherapy.

Administration, Intravesical↗
PubMed1987

[Spermatogenesis].

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Androgen-Binding Protein↗
PubMed1987

[Effects of cilastatin sodium, an inhibitor of dehydropeptidase-I, on human urinary peptide excretion. Patients with renal insufficiency].

Effects of imipenem/cilastatin sodium (IPM/CS), a new parenteral carbapenem combination antibiotic, on the excretion of urinary peptides were investigated by amino acid analysis of these peptides from 12 patients with varying degrees of impairment of renal function, after single or multiple doses (9 doses) of 500 mg/500 mg of the combination drug administered by 30-minute drip infusion. In a single dose study, slight increase in glycine (Gly) were observed in patients with mildly impaired renal function (group I). On the other hand, several amino acids including aspartic acid (Asp), glutamic acid (Glu), Gly and alanine (Ala) were increased in patients with moderately (group II) and severely (group III) impaired renal function. Gly showed the greatest increase, 1.029 microM/mg creatinine.2 hours, and the value was 2.4 times as high as the control collected before drug administration. These values were reduced to the control levels within 10-12 hours after the drug administration for amino acids showing small increases and within 12-24 hours after drug administration even for those showing greater increases. In a multiple-dose study employing 3 patients with moderately impaired renal function, Asp and Gly were found to increase after the 1st, 5th and 9th doses. The increased amino acids were reduced to preadministration levels within 10-12 hours or faster, and no tendency for accumulation was observed. From the above results, CS, as a dehydropeptidase-I inhibitor apparently caused increases in some peptides consisting mainly of Asp, Glu, Gly and Ala in patients with impaired renal function. A careful selection of dose levels and frequency of administration will be required in patients with moderately or severely impaired renal function.

Aged↗