Biomedical subjects

M Okada

Publications and source records attributed to M Okada.

At least 1,171 records · Page 65Linked to original sources

PubMed1990

Analysis of cytoplasmic activity dependent on the Drosophila terminal pattern gene torso.

Cytoplasm from wildtype Drosophila embryos was transplanted into torso (tor) mutant embryos to determine the distribution of terminal rescuing activity at the cleavage stage. Although posterior and lateral wildtype cytoplasm contained rescuing activity that restored posterior terminal (telson) structures Klingler et al. (1988, Nature (London) 335, 275-277) this rescuing activity was not found in anterior cytoplasm. Similarly, transplantation of anterior and lateral wildtype cytoplasm into the anterior of tor embryos rescued anterior terminal (acron) structures, whereas posterior cytoplasm did not. This failure of reciprocal rescue is due to the presence of the products of the anterior and posterior classes of genes, because anterior cytoplasm from bicoid mutant embryos restored the telson in the posterior as well as the acron in the anterior of tor embryos, and because posterior cytoplasm from nanos embryos rescued the acron in the anterior as well as the telson in the posterior of tor embryos. Therefore terminal rescuing activity is evenly distributed throughout the cleavage stage embryo as anticipated from molecular studies.

Animals↗

PubMed1990

Proteolytic elimination of decay-accelerating factor (DAF): lytic abnormality coincides with removal of DAF in papain-treated human erythrocytes.

Erythrocytes (E) from patients with paroxysmal nocturnal hemoglobinuria (PNH) lack decay-accelerating factor (DAF) and this partly causes increasing susceptibility of the E to complement. Several reagents have been used to convert normal E to the complement-sensitive (PNH-like) cells. The relationship between DAF amounts and complement susceptibility of these PNH-like cels has been examined. Of the reported reagents for preparation of PNH-like cells, 2-amino-ethylisothiouronium bromide (AET), papain, and periodate efficiently converted normal E to the complement-sensitive cells, but only papain reduced the quantity of DAF on the cells. Further, of the proteases we tested only papain cleaved DAF to liberate its major fragment from the cells. The papain-treated cells lysed in a similar fashion to PNH cells as the serum concentration increased. The major papain-digested product of DAF had Mr, 55,000, lacked hydrophobicity, and retained the ability to inhibit the C3 convertases. These findings suggest that papain allows liberation from cells of functional domains as well as most of the antigenic epitopes of DAF to generate a PNH-like cell.

Blood Proteins↗

PubMed1990

c-myb gene analysis in T-cell malignancies with del(6q).

Three T-cell malignancies with del(6q) were analyzed for karyotypes and alteration of the oncogene c-myb that is assigned to 6q22-q24. Patients were diagnosed as having non-Hodgkin T-cell lymphoblastic lymphoma, adult T-cell leukemia, and acute T-cell lymphoblastic leukemia, and the deletions of chromosome 6 were del(6)(q21q25), del(6)(q21q23), and del(6)(q21) or del(6)(q21q27), respectively. Tumor cell DNAs were obtained from cultured pleural fluid or from fresh peripheral blood and marrow samples and were analyzed by Southern blot hybridization, using c-myb oncogene probes. Rearrangements, deletions, or amplifications were absent in these tumor DNAs, thereby indicating that the del(6q) breakpoint in these T-cell malignancies was located outside of the c-myb gene. Northern blot analysis revealed the elevated expression of c-myb in the non-Hodgkin lymphoma patient, in accord with lineage characteristics.

Adolescent↗

PubMed1990

Proteinaceous inhibitors of phospholipase A2 purified from inflammatory sites in rats.

We have purified two phospholipase A2 inhibitory proteins (37 and 33 kDa) from peritoneal fluid of dexamethasone-treated rats. The extracellular phospholipase A2 found in inflammatory sites differed from the exocrine phospholipase A2 in susceptibility to these endogenous inhibitors; both proteins inhibited the activity of the extracellular phospholipase A2 purified from sites of inflammation but did not affect appreciably the activity of either porcine pancreatic or Naja naja venom phospholipase A2. The amino acid sequence of the NH2-terminal portion of the purified proteins did not resemble that of lipocortins so far reported, but it was almost identical to that of parts of human or mouse complement component C3. These findings may indicate that degraded products of C3 are involved in the regulation of activity of a class of mammalian phospholipase A2.

Amino Acid Sequence↗

PubMed1990

Determination of antigenic epitopes recognized by four monoclonal antibodies to glutathione S-transferase pi (GST-pi).

Four independent antibodies (6A, 5F, 2H and 2F) to Glutathione S-transferase pi (GST-pi) were selected to characterize their epitopes. Amino acid analysis of 5.6 K and 7.4 K tryptic peptides appeared to suggest that the epitope recognized by antibodies 2H and 2F is located in the N-terminal 44 peptides of GST-pi, and that of 6A and 5F is located in the C-terminal 69 peptides. Reactivities of antibodies 6A and 5F with two synthetic peptides indicated that 6A recognized an epitope in the C-terminal hydrophilic fragment 176Leu-209Gln, and could be distinguished from 5F which recognized an epitope in the 141Thr-176Leu hydrophobic fragment. The differential immuno-reactivity of antibodies 6A and 5F with GST-pi itself, was characterized by the particularly high reactivity of 6A and almost no reactivity of 5F with the natural conformation of GST-pi in solution. This may be explained by differences in the hydropathic natures of their epitopes. The 6A antibody was useful for immunodetection of GST-pi in circulation, while 5F was found to be most suitable for histochemical staining of tumor tissue.

Amino Acid Sequence↗

PubMed1990

Regulation of proteolytic activity of complement factor I by pH: C3b/C4b receptor (CR1) and membrane cofactor protein (MCP) have different pH optima for factor I-mediated cleavage of C3b.

C3b/C4b receptor (CR1) and membrane cofactor protein (MCP) are integral membrane glycoproteins with factor I-dependent cofactor activity. They bind to C3b, allowing factor I to cleave C3b at two sites (first and second cleavage), which results in the generation of C3bi, a hemolytically inactive form which is a ligand for complement receptor type three (CR3). C3bi is further degraded by factor I and CR1 (third cleavage) to C3dg (a ligand for complement receptor type two, CR2) and C3c. Using two different substrates, fluid-phase C3b and cell-bound C3b, the cleavage of C3b by MCP and factor I was compared to that by CR1 and factor I under various conditions. The optimal pH for the first and second cleavage of either substrate was 6.0 for MCP and 7.5 for CR1. The third cleavage was mediated only by CR1 and factor I, the optimal pH being 8.0. Low ionic conditions enhanced the C3b binding and cofactor activity of both CR1 and MCP. The efficiency of binding C3b to CR1 or MCP was maximal at pH 6.2. The isoelectric point (pI) of MCP was acidic (approximately 4.0), while that of CR1 was 6.8. Therefore, compared to CR1, MCP possesses distinct functional profiles relative to C3b-binding and factor I-cofactor activity.

Antigens, CD↗

PubMed1990

Increased microvascular permeability and lesion formation during gastric hypermotility caused by indomethacin and 2-deoxy-D-glucose in the rat.

The relationship between lesion formation, gastric motility, and vascular permeability was examined in rats using indomethacin and 2-deoxy-D-glucose (2DG). Both indomethacin (25 mg/kg s.c.) and 2DG (100 mg/kg/h i.v.) produced gastric hypermotility and induced lesions, mostly confined to the rugal crests of the mucosal folds; the onset of hypermotility preceded appearance of the lesions in both cases. The mucosal microvascular permeability as determined by the amount of extravasated dye (Evans blue) was increased in response to these two agents, and the permeability responses also preceded appearance of the lesions. Both the increased vascular permeability and the severity of lesions were significantly reduced when the hypermotility was inhibited by pretreatment with atropine (3 mg/kg s.c.). The severity of the lesions were also markedly reduced or worsened, respectively, by hydrocortisone (10 mg/kg s.c.) or N-ethylmaleimide (10 mg/kg s.c.) at the doses that significantly decreased or enhanced the vascular permeability responses caused by indomethacin and 2DG. These results suggest that the enhanced gastric motility as induced by indomethacin and 2DG may cause microcirculatory disturbances in the specific sites of the mucosa (mucosal folds), probably by abnormal compression of the gastric wall, leading to the increased microvascular permeability and cellular damage.

Animals↗

PubMed1990

Human platelets effectively kill K-562 cells, a chronic myelogenic leukemia cell line, in vitro.

The cytotoxic effect of isolated human platelets on leukemic cells has been examined in order to investigate the role of platelets in host defense systems. K-562 cells (a chronic myelogenic leukemia cell line) showed significant change in their morphology and were killed when they were incubated with platelets in serum-free medium for several hours at 37 degrees C, a condition where no killing of normal peripheral lymphocytes occurred. Some protease inhibitors inhibited the cytotoxicity of platelets against K-562 cells. Our results suggest that platelets may be involved in host defense against neoplasia and that certain proteases are implicated in the cytotoxic effect of platelets.

Blood Platelets↗

PubMed1990

The in vivo anti-tumor effect of human recombinant interleukin-6.

Administration of recombinant interleukin-6 (IL-6) was found to induce in vivo generation of cytotoxic T lymphocytes (CTL) against syngeneic transplantable erythroleukemia (FBL-3) in lymph node cells and peritoneal exudate cells (PEC) in C57BL/6 mice. Furthermore, 15 out of 16 C57BL/6 mice injected with 5 x 10(6) viable FBL-3 cells survived on day 100 when they were treated with 5 x 10(4) U of recombinant IL-6 three times a day on days 1, 2, 3, 5, 7 and 9 after the inoculation of tumor cells (the cure rate was 94%). Cured mice could reject the tumor cells rapidly after the re-inoculation of a large number of live FBL-3 cells. In contrast, all normal mice died of tumor development by day 10. In these cured mice, FBL-3-specific CD4-8+ CTL cells were found to be generated in PEC, spleen and lymph node cells by either in vivo or in vitro re-stimulation with FBL-3 cells, but lymphokine-activated killer cells never developed. The results suggested that the anti-tumor effect of IL-6 was mediated by in vivo induction of tumor-specific CTL.

Animals↗

PubMed1990

Induction of eosinophilic colonies by interleukin-5 on acute myeloblastic leukaemic cells.

The effect of interleukin-5 (IL-5) on blast colony formation of acute myeloblastic leukaemia (AML) cells was studied. IL-5 showed a weak but significant colony stimulatory effect in one out of six cases studied. IL-5 induced eosinophilic colony growth in this case, and chromosomal and histochemical analyses strongly suggested that these eosinophilic colonies were derived from leukaemic blast progenitor cells. To our knowledge, this is the first report that IL-5 induces eosinophilic colonies on fresh AML cells. A possible induction of differentiation of AML blast cells by IL-5 is suggested.

Adult↗

PubMed1990

Differential calcium dependence between the release of endogenous dopamine and noradrenaline from rat brain synaptosomes.

The characteristics of the release of endogenous dopamine and noradrenaline from rat brain synaptosomes were studied using HPLC with an electrochemical detector. The spontaneous release of dopamine and noradrenaline was inhibited by approximately 50-60% in a Ca2(+)-free medium or a 100 microM La3(+)-containing medium. Also, the high-K+ (30 mM)-evoked release of dopamine and noradrenaline was inhibited by approximately 50-60% in a Ca2(+)-free medium or a 100 microM La3(+)-containing medium. From these results, the ratio of the Ca2(+)-dependent component to the total release of noradrenaline seemed to be similar to that of dopamine. On the other hand, 20 microM La3+ or 1 microM diltiazem inhibited both the spontaneous and 30 mM K(+)-evoked release of dopamine by approximately 50-60% but inhibited neither the spontaneous nor the 30 mM K(+)-evoked release of noradrenaline. The K(+)-evoked rise in intrasynaptosomal Ca2+ concentration was mostly blocked in Ca2(+)-free medium or 100 microM La3(+)-containing medium but was only partially blocked by 20 microM La3+ or 1 microM diltiazem. These data indicate alternative possibilities in that the Ca2(+)-dependent release of noradrenaline might be less sensitive to a change of intracellular Ca2+ concentration than that of dopamine and that the calcium channels directly involved in the noradrenaline release may be more resistant to diltiazem and La3+ than those involved in the dopamine release.

Animals↗

PubMed1990

In vitro susceptibility of Campylobacter jejuni to rokitamycin.

The susceptibilities of 100 clinical isolates of Campylobacter jejuni to rokitamycin, a new macrolide, and eight other oral antibiotics were tested by using a broth microdilution method. Rokitamycin demonstrated antibacterial activity that was higher than those of fosfomycin and the tetracyclines and comparable to those of erythromycin and clindamycin, whereas it was slightly less active than the quinolones.

Anti-Bacterial Agents↗

PubMed1990

Predictors of duodenal ulcer healing during treatment with cimetidine.

A two phase study was performed to identify factors that influence the healing rate of duodenal ulcer. The study included an initial clinical trial in 145 patients and a second trial in a further 61 patients. All patients were prescribed cimetidine at a daily dose of 800 mg for six weeks. The factors examined were age, sex, inpatient or outpatient treatment, duration of present ulcer pain, past history of duodenal ulcer, smoking, drinking, the length of time it took for symptoms to resolve after beginning treatment, and the characteristics of the ulcers themselves. Eighty four per cent of the duodenal ulcers healed after six weeks. Using univariate and multivariate analyses, it was found that three factors indicated a significant delaying effect on healing: (1) symptoms that persisted two weeks after treatment had begun; (2) heavy smoking (20 or more cigarettes daily); and (3) severe narrowing of the duodenal bulb. Patients with none of the three unfavourable factors (n = 90) had a healing rate of 95.6% compared with patients with one (n = 45) or two or more (n = 10) factors, whose healing rates were 75.6% and 20.0% respectively (p less than 0.001). The corresponding figures in a second study were 88.9%, 55.0%, and 0%, respectively (p less than 0.001). A prognostic score based on these three factors represents the severity of duodenal ulcers with regard to healing in patients treated with cimetidine.

Adult↗

PubMed1990

[How to discriminate between vibration syndrome and local fatigue of motorcyclists].

Motorcyclists who work in some offices sometimes complained of coldness, pain and numbness of upper limbs. We studied how to discriminate between vibration syndrome and local fatigue of the motorcyclists. Subjects are 42 motorcyclists of an office in Aichi prefecture. 25 of them held several letters in their left hand when they delivered the letters. They complained of coldness, pain and numbness in the left upper limbs more than in the right limbs (p less than 0.01). We think that it is the local fatigue rather than the disorder of vibration syndrome that causes such symptoms. So it is very important to recognize the existence of local fatigue in order to know how to discriminate between vibration syndrome and local fatigue of the motorcyclists.

Adult↗

PubMed1990

[Teeth arrangement of anterior artificial teeth. 1. Age and teeth exposure].

In selecting and arranging anterior artificial teeth for edentulous patients, it is necessary to consider their sex, personality, age and other factors. The relation of upper and lower lip lines to incisal edge has been one of the standards for the selection and the arrangement of anterior artificial teeth. The purpose of this report was to establish and to evaluate decision bases for the selection and arrangement. We recorded and measured the exposure rate of anterior natural teeth (48 men, 46 women) during function, such as smile, pronunciation, by means of the image analysis. Following results were obtained. 1. As the age of patients increased, upper anterior teeth appeared less than lower's. 2. Differences in exposure ratio between upper and lower teeth were found more remarkable in smiling rather than in pronunciation.

Adult↗

PubMed1990

Method for quality control of laboratory tests using histograms of daily patient data.

A method for controlling the quality of laboratory tests is proposed. Histograms of patients' daily results which fall within reference ranges of healthy individuals are used for estimating accuracy and precision of measurements. For the determination of accuracy, three methods are evaluated; computing an average of patients' results; determining the location of the peak of the histogram; approximating the histogram by an Erland distribution and determining the peak of the distribution. For precision control, standard deviations are calculated from patient data. We applied these methods to serum aspartate aminotransferase (AST or SGOT) and total cholesterol of patients in a general hospital. Averages, peaks of approximated Erland distribution, and standard deviations were found to be useful to daily quality control in laboratories of large hospitals.

Aspartate Aminotransferases↗

PubMed1990

[Combination chemotherapy with bleomycin ointment and lysozyme ointment against mouse WHT squamous cell carcinoma].

The antitumor effect of bleomycin (BLM) ointment in combination with lysozyme (LY) ointment was investigated. Nine-week-old male and female WHT/Ht mice were implanted with a graft of WHT squamous cell carcinoma into the subcutis of back, and the skin covering the developed solid tumor was resected 7 days after implantation. Thereafter, the mice were administered twice daily for 7 days with each of the following: 220 mg of 0.25% BLM ointment, 2.5% LY ointment, and a 1:1 mixture of 0.5% BLM ointment plus 5% LY ointment. BLM ointment and the combination of BLM ointment and LY ointment were effective with an inhibition rate of 79.3 and 89.7%, respectively. The inhibition rates of these groups showed a statistically significant increase over that of control group. Further, the rate of the combination group displayed a statistically significant increase over that of the BLM ointment group. Formation of crusta on the solid tumor was markedly inhibited in the groups applied LY ointment and the combination of LY ointment and BLM ointment. LY was ineffective against cultured cells of WHT squamous cell carcinoma and did not potentiate the antitumor activity of BLM in combination. These results suggest that potentiation of the antitumor effect of BLM ointment in combination with LY ointment is due to inhibition of crusta formation by LY resulting in an increased permeation of BLM into tumor tissue.

Animals↗

PubMed1990

[Computer technology in clinical preventive medicine].

Predicting who will suffer from diseases in the future is basically mathematical work. Current computer technology will accelerate the progress of preventive medicine. In this respect, there are two useful tools for the research. First, long-term archiving of health-care information is valuable in a retrospective study, such as, determination of diagnostic criteria for the prediction. Health-care information here includes past history, laboratory data, and dietary habits. Using such criteria, potential patients can be discriminated from truly healthy persons. Second, prediction is successfully carried out on the basis of mathematical equations which represent the relationship between disease status and health-care information. In conclusion, technology for database management and mathematical modelling is essential for the basic study in preventive medicine.

Blood Banks↗