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S Sekiguchi

Publications and source records attributed to S Sekiguchi.

At least 127 records · Page 7Linked to original sources
PubMed1994

Lysophosphatidylcholine, a component of stromal phospholipids, as a candidate vasoconstrictive factor in stroma-free hemoglobin.

Stroma-free hemoglobin (SFH) contains a trace amount of phospholipids, which has been implicated in the toxic reactions associated with SFH. We analyzed stromal phospholipids by high-performance liquid chromatography and found that SFH contained small quantities of lysophosphatidylcholine (LPC), which is known to be capable of producing a defect in endothelium-dependent arterial relaxation, in addition to major classes of constituent phospholipids in red cell membrane. LPC content was determined to be 1.65 nmol/ml (hemoglobin 8.1 g/dl). To evaluate the role of these stromal phospholipids in SFH-induced vasoconstriction, we next examined the effect of lipids on vascular tone in rabbit aortic strips. Preincubation with the crude lipid extract or the LPC purified from SFH significantly inhibited acetylcholine-induced relaxation in phenylephrine-precontracted tissues. The LPC-induced inhibition was reversed by incubation of the tissues in the absence of lipids, indicating the functional integrity of endothelium. From these results, we propose a possibility that LPC, a component of stromal phospholipids, is a candidate for vasoconstrictive factors present in SFH.

Acetylcholine↗
PubMed1994

Distribution of epidermal growth factor and epidermal growth factor receptor in human lung: immunohistochemical and immunoelectron-microscopic studies.

The distribution of epidermal growth factor (EGF) and EGF receptor (EGFR) in adult human lung was examined by immunohistochemistry and immunoelectron microscopy. EGF immunoreactivity was observed in secretory granules and endoplasmic reticulum of serous acinar cells of bronchial glands. EGFR immunoreactivity was detected at the cell membrane of the basal cells and the bronchial surface nonciliated cells (indifferent cells) in the bronchus, the nonciliated bronchiolar cells (Clara cells) and the type II pneumocytes in peripheral lung. These results suggest that EGF is secreted into bronchial surface fluid from the bronchial glands and stimulates proliferation and/or differentiation of basal cells and indifferent cells of the bronchus, although the source of EGF responsive to Clara cells and the type II pneumocytes of peripheral lung was not determined.

Aged↗
PubMed1994

Generation of active oxygens, cell deformation and membrane potential changes upon UV-B irradiation in human blood cells.

The generation of peroxides (presumably hydrogen peroxide) by UV-B irradiation of human blood cells was detected. Non-fluorescent dihydrorhodamine 123 (DHR) is oxidized to fluorescent rhodamine 123 (R123) by H2O2 or peroxides with a stoichiometry of 1:1 in the presence of exogeneous peroxidase, and the fluorescence of R123 within the cells was measured using flow-cytometry. UV irradiation gave rise to changes in the cellular volume and the membrane potential, whose extent and direction were dependent on the type of blood cells. The production of peroxides (H2O2) in polymorphonuclear leukocytes is the largest among blood cells at the lower dose (< 0.1 J/cm2), and the production decreases with an increase in the dose, while the production in platelets is the smallest at the lower dose, but above 0.4 J/cm2 it increases suddenly so that at the higher dose (1.2 J/cm2) it amounts to 3.3 x 10(-16) mol/cell. For monocytes and lymphocytes, the production increases gradually with the increase in the dose.

Blood Cells↗
PubMed1994

Acellular and cellular hemoglobin solutions as vasoconstrictive factor.

The inhibitory effects of acellular and cellular hemoglobin (Hb) solutions on endothelium-dependent vasorelaxation were investigated in rabbit thoracic aortic strips. As acellular Hb solutions, 2,3-diphosphoglycerate (DPG)-depleted Hb and pyridoxylated Hb were examined. Cellular Hb solutions included washed human fresh red cells and liposome Hb encapsulated with pyridoxal-5'-phosphate (PLP). The tissues were precontracted with phenylephrine (PE), after which acetylcholine (ACh) was added to elicit a steady-state relaxation. Acellular Hb solutions cumulatively reversed ACh-induced relaxation, and these inhibitory effects reached a plateau at 10 micrograms/ml. Increasing oxygen affinity by pyridoxylation had little effect on this. In contrast, both red cells and liposome Hb solution showed moderate inhibitory effects, and they reached a plateau at 1 mg/ml. These findings indicate that acellular Hb solutions are more potent inhibitors than cellular Hb solutions by a factor of about 100, and that the encapsulation of Hb is a preferable method to mimic the red cell.

2,3-Diphosphoglycerate↗
PubMed1994

Oxygen transport and in vivo parameters of artificial red cells (ARC).

Artificial red cells (ARC) are prepared by encapsulating Hb with a polymerizable phospholipid. Their physical stability is very high and long-term preservation is possible in the frozen state. We examined the effect of blood parameters on the hematological and biochemical findings in transfused rats. The oxygen transport capacity of ARC in vivo were also tested by exchange transfusion in beagles. The oxygen binding parameters were almost the same as those of red blood cells (i.e., P50, Hill's coefficient, and oxygen transport efficiency (OTE) were 30 mmHg, 2.5, and 30%, respectively). The blood parameters after transfusion showed no significant changes when compared with the control. The oxygen transport capacity was of the same efficiency as red blood cells.

Animals↗
PubMed1994

The quality control of stroma-free hemoglobin: lysophosphatidylcholine, a component of stromal phospholipids, as candidate vasoconstrictive factor.

We characterized stromal phospholipids in stroma-free hemoglobin (SFH) by normal-phase and cation-exchange HPLCs, and found that SFH contained not only four phospholipids which were the major constituent classes in membrane, but also several peaks which were not yet identified. The residual amounts of these lipids in SFH were changed with storage of red cell concentrates. The four major phospholipids decreased concomitantly with storage, whereas the unidentified peaks increased after 21 days and then decreased after 48 days. We also found that SFH contained lysophosphatidylcholine (LPC) at 5.71 micrograms/ml, which was the deacylated metabolite of phosphatidylcholine (PC). These results suggest that stromal phospholipids are degradable. Since LPC is known to be capable of producing a defect in endothelium-dependent arterial relaxation, we next examined the effect of stromal lipids on vascular tone in rabbit thoracic aortic strips. Preincubation with the crude lipid extract or the LPC purified from SFH by TLC significantly inhibited acetylcholine (ACh)-induced relaxation in phenylephrine (PhE)-precontracted tissues. These observations have led to the proposal that LPC, a component of stromal phospholipids, induces vasoconstriction as a result of inhibition of endothelium-dependent vasorelaxation.

Animals↗
PubMed1994

A time course study for optimal harvest of peripheral blood progenitor cells by granulocyte colony-stimulating factor in healthy volunteers.

In a search for the optimal method to harvest peripheral blood progenitor cells (PBPC) without myeloablative chemotherapy, we administered recombinant human granulocyte colony-stimulating factor (G-CSF) to adult, healthy volunteers and investigated the mobilization rate of the PBPC. The consecutive subcutaneous administration of G-CSF in a dose of 2 micrograms/kg/d for 5 days significantly increased colony-forming units-granulocyte/macrophage (CFU-GM) up to 2340 +/- 980 per mL whole blood with a 30 +/- 21-fold mobilization of PBPC, range 11- to 76-fold. Burst-forming units-erythroid (BFU-E) and mixed erythroid progenitors (CFU-Mix) were also increased, and the mobilization rate was 8.4 +/- 4.5-fold and 7.6 +/- 4.7-fold, respectively. A time course study of PBPC after final G-CSF injection was done for 0 to 30 hours on days 1, 3, and 5. After a single administration of G-CSF (day 1), there was no increment of PBPC during the subsequent 30 hours, but the white blood cell count (WBC) markedly increased. Three days after the injection of G-CSF, no increase of CFU-GM was seen during the first 2 hours, then a significant, time-dependent increase occurred for up to 30 hours. Five days after the injection of G-CSF, there was no increase of CFU-GM during the first 2 hours, and the significant increase at 24 hours was maintained for up to 30 hours. BFU-E and CFU-Mix showed the same pattern of expansion as seen with CFU-GM. Thus, subcutaneous administration of 2 micrograms/kg/d G-CSF for 5 days will lead to a successful PBPC harvest for transplantation, and the most suitable period for this is 24 to 30 hours after the final G-CSF administration.

Adult↗
PubMed1994

Transitional changes in immunophenotypic subpopulations of human peripheral blood CD34+ cells expanded in vitro.

We determined the appropriate incubation period to expand human peripheral blood (PB) CD34+ cells for clinical application and the role of recombinant human (rh) interleukin-3 (rhIL-3) in the expansion and differentiation of these cells. The cells were purified up to 40 +/- 16% and transitional changes in immunophenotypic subpopulations in suspension culture were examined following stimulation with three different combinations of rh colony-stimulating factors (rhCSFs): 1) rhIL-3 alone, 2) rhIL-6, rhSCF, rhG-CSF, plus rhGM-CSF, and 3) the four CSFs plus rhIL-3. With all three CSF combinations, the total cells increased continuously after day 5 until day 14, and a combination of the five CSFs always gave rise to the highest number of total cells. Immunophenotypic analysis of the expanded cells showed that with all three CSF combinations CD34+ cells reached a maximal rate on day 5 and then decreased in an inverse correlation between the logarithm of CD34 positive rate and the duration of suspension culture. The maximum expansion of CD34+ cells and PB progenitor cells (PBPC) with rhIL-3 alone, the four CSFs, or the five CSFs was observed on day 5, 10, or 7, respectively. The combination of the five CSFs was identified as the most potent stimulus for expansion of PBPC and CD34+ cells, as it increased non-erythroid PBPC 89 +/- 69-fold, with a range of 24 to 204-fold on day 7. However, differences in the expansion rate of these cells on days 5, 7, and 10 were not statistically significant. The majority of purified CD34+ cells coexpressed CD38 (91 +/- 3%) but were negative for CD33 (85 +/- 4%), and one-half coexpressed CD13. With all three combinations of CSFs, the mature CD34+ cells that coexpressed CD38, CD33, or CD13 expanded in parallel with the total CD34+ cells, while an increase in relatively immature CD34+ cells, which do not express CD38, CD33, or CD13, was only statistically significant with the five CSFs. Thus, rhIL-3 played a critical role when combined with the four CSFs by increasing both mature and immature CD34+ cells.

Adult↗
PubMed1994

[Application of inflammation markers in the "essential laboratory tests" to new outpatients and analysis for the efficacious selection of these items].

We have re-evaluated the usefulness of the inflammation markers in the "essential laboratory tests" advocated by Japan Society of Clinical Pathology and analyzed for efficacious selection of these items by applying these tests to 349 new outpatients visited Comprehensive Medicine, National Defense Medical College. Among the patients with "tentative initial diagnoses" of infectious or inflammation-related diseases (133 cases), the diagnoses were confirmed in 102 patients by positive inflammation marker(s), whereas additional 22 cases with the diagnoses other than inflammation-related diseases were found to be in the inflammatory status by these tests. Elevated C-reactive protein (CRP) levels were not correlated with the leukocyte number, however, neutrophilia (neutro. > 70%) and/or left shift of the neutrophils (stab > 15%) were demonstrated in approximately 50% of the patients with elevated serum CRP levels. Increases of serum sialic acid highly accompanied with increases of CRP, alpha 1 or alpha 2 fraction of serum protein and elevation of erythrocyte sedimentation rate (ESR), indicating that serum sialic acid levels reflected more strictly inflammatory status than ESR. There is a relatively good correlation (r = 0.813) between serum sialic acid values and the total amounts of alpha 1 and alpha 2 protein fraction, while poor correlations were shown between CRP and sialic acid values (r = 0.606), or ESR and sialic acid values (r = 0.671). These results indicate that (1) simultaneous measurements of CRP, leukocyte number and leukocyte differential fraction are useful for the confirmation of early stage of inflammation and evaluation of the nature of infectious diseases; (2) measurement of serum sialic acid levels is more desirable for the evaluation of inflammatory status than ESR; and (3) serum protein profile can be substituted by sialic acid for the evaluation of acute inflammatory status alone.

Adolescent↗
PubMed1994

[Asymptomatic bilateral spontaneous pneumothorax].

Two surgical cases of bilateral pneumothorax founded at a medical examination were reported. Case 1; A 15-year-old male was admitted to our hospital pointed out left spontaneous pneumothorax without complaints. The interval between the first and the contralateral pneumothorax was 3 weeks. He was treated with a one-stage operation through a bilateral axillary incision. Case 2; A 19-year-old male was admitted to our hospital pointed out left spontaneous pneumothorax without complaints. Surgical operation was performed with a left axillary incision. One year after the treatment, he was pointed out right spontaneous pneumothorax on his chest X-ray film. Partial resection of the right lung was performed with a right axillary incision. Of the 261 pneumothorax patients, 28 had bilateral pneumothorax in our hospital. The majority of these patients had complaints which were chest pain, dyspnea and cough. Of the 28 patients, 2 had no complaints at the time of admission. We conclude that we have to follow up carefully the patients with hemilateral spontaneous pneumothorax.

Adolescent↗
PubMed1994

[4-Log leukocyte depletion of erythrocyte concentrates--a comparison with 3 other filters].

Whole blood (WB) and SAGM-resuspended red cell concentrates (RCC) were leucocyte-depleted 1 h after donation by filtration using BF 4 (PALL), Sepacell RS 200 (Asahi Med.) and Bio R01 Plus (Biotrans). We compared the handling of the filter system, focusing routine blood bank practice, filtration efficiency [residual white cell count; flow cytometry (Ortho Cytoron) and Nageotte chamber] and the loss of red cells. Spontaneous filling was found to be an advantage of the Bio R01 Plus system, whereas the BPF 4 and the RS 200 have to be filled by pressure. The filtrations were of similar duration, even those of WB and resuspended RCC. Red cell loss was found to be 10-15% on RCC higher than on WB (7-10%) and varied between the filters used: BPF 4 < Bio R01 Plus < RS 200. The residual white cell count on WB was 1.2-5.8 x 10(6) (RS 200 < Bio R01 Plus < BPF 4) and on RCC was 0.5-3.0 x 10(5) (RS 200 < BPF 4 < Bio R01 Plus). The filters used are highly effective (4-log depletion on RCC) even on fresh WB and are therefore potential in-line filters.

Blood Donors↗
PubMed1993

In vitro expansion of human peripheral blood CD34+ cells.

To elucidate the role of recombinant human colony-stimulating factors (CSFs) for expanding peripheral blood (PB) CD34+ cells, these cells were purified up to 94.5% +/- 1.3% and the effects of individual and combined CSFs on the proliferation and differentiation of these cells were studied in a 7-day suspension culture. The majority of CD34+ cells coexpressed CD38 (81.8% +/- 5.1%), but was negative for CD33 (88.5% +/- 3.4%). Among the individual CSFs examined, recombinant interleukin-3 (rIL-3) was identified as the most potent factor for expanding PB progenitor cells and increased nonerythroid progenitor cells 13- +/- 4-fold (P < .01). Recombinant granulocyte-macrophage colony-stimulating factor (rGM-CSF), recombinant granulocyte-CSF (rG-CSF), recombinant macrophage-CSF (rM-CSF), rIL-6, rIL-11, and recombinant stem cell factor (rSCF) did not alone expand nonerythroid progenitor cells. A combination of 5 CSFs, ie, rIL-3, rIL-6, rGM-CSF, rG-CSF, and rSCF, was identified as the most potent combination of those tested and increased nonerythroid progenitor cells 57- +/- 11-fold. After a 7-day suspension culture of CD34+ cells with these 5 CSFs, CD34+ cells expanded 14.5-fold, and CD34+/CD33- cells and CD34+/CD33+ cells were also expanded 2.9-fold and 307-fold, respectively. Most secondary colonies derived from expanded cells were small; however, the absolute number of large-sized colonies expanded 5.9- +/- 3.3-fold. Thus, the combination of CSFs can achieve a degree of amplification of PB CD34+ cells. The capability of in vitro expansion of PB CD34+ cells as an adjunct to PB stem cell transplantation is worthy of consideration.

Adult↗
PubMed1993

UV irradiation can induce in vitro clonal anergy in alloreactive cytotoxic T lymphocytes.

The alloreactive cytotoxic T lymphocytes (CTL) were generated by coculturing peripheral blood mononuclear cells (PBMC) with allogeneic Sa cells (an Epstein-Barr virus [EBV]-transformed B-cell line). The CTL did not proliferate in response to UV-B-irradiated Sa cells unless exogenous interleukin-2 (IL-2) was present, although they could kill the UV-B-irradiated Sa cells. The results indicate that UV-B-irradiated Sa cells do not provide sufficient signals for the proliferation of the CTL while they can be recognized by CTL and induce high-affinity IL-2 receptor (IL-2R) expression on them. The alloreactive CTL could be rendered anergic by previous exposure to UV-B-irradiated Sa cells. The alloreactive CTL previously stimulated with UV-B-irradiated Sa cells failed to proliferate in response to nontreated Sa cells. Proliferation of the anergic CTL could not be restored by Sa cells and exogenous IL-2 but by the combination of phorbol 12-myristate 13-acetate (PMA) and calcium ionophore (A23187). The anergic CTL showed a considerably low cytotoxic activity against Sa target cells. The expression of TCR on the anergic CTL was downregulated while expression of high-affinity IL-2R was upregulated. Their CD28 and CD8 expression were unchanged. In addition, the proliferative response and cytotoxicity of the anergic CTL to Sa cells could be restored after the cells had been rested for 7 days to allow reexpression of TCR. These results suggest that downregulation of T-cell receptor (TCR) and impairment in the post-IL-2/IL-2R signaling pathway are relevant to the clonal anergy induced in the alloreactive CTL by stimulation of UV-B-irradiated Sa cells.

Antigens, CD↗
PubMed1993

The epidemiology and infection route of asymptomatic HCV carriers detected through blood donations.

The Japan Red Cross started screening donated blood for anti-HCV in Nov. 1989. Approximately 0.9% of donors were found to be positive by the 1st generation antibody test. The authors started a carrier clinic for the medical care of apparently healthy HCV carriers. Donors whose antibodies were strongly positive both by 1st EIA and 2nd PHA were informed, and were confirmed by RIBA 2 and RT-PCR. A total of 262 carriers (150 males and 112 females) with mean age of 46.8 +/- 11.2 yrs have visited the clinic. Of these carriers 149 were diagnosed to be asymptomatic clinically, biochemically and echographically. Eighty-seven carriers had received blood transfusions 22.7 +/- 10.9 yrs previously, while 106 had had acupuncture. Sixty had a family history of liver disease. Fifty-four had a history of heavy alcohol intake. Tattoos and/or iv drug abuse were found in 11, and nosocomial needle accidents in 4. HBV antibodies were found in 145 cases (55%). In conclusion, approximately 60% of HCV carriers found at the time of blood donation were apparently asymptomatic, suggesting the need of longer follow-up. Main routes of infection were estimated to be blood transfusion (33%), other parenteral exposure routes (6%), household (10% or less), and acupuncture (20% or less), considering duplication and priority.

Blood Donors↗
PubMed1993

Ultraviolet irradiation inhibits killer-target cell interaction.

The effects of ultraviolet (UV) irradiation on cell-mediated cytolysis were examined in order to clarify the inhibitory mechanisms of allosensitization by UV irradiation. UV-B-irradiated target cells (Sa; an Epstein-Barr virus-transformed B cell line) exhibited more resistance against alloreactive cytotoxic T lymphocytes (CTL) than mitomycin C (MMC)-treated target cells. In the conjugate formation assay, UV-B-irradiated target cells showed a considerably lower binding to alloreactive CTL than MMC-treated target cells. UV-B irradiation induced a reduction of HLA-class I, -DR, CD54 (ICAM-1) and CD58 (LFA-3) expression on target cells. However, it does not seem to contribute to the inhibition of cell adhesion induced by UV-B irradiation because a similar reduction of cell surface antigens was observed in MMC-treated target cells. Number of cells capped with anti-HLA-class I, -DR, CD54 or CD58 monoclonal antibody were markedly reduced by UV-B irradiation compared to that by MMC treatment. These findings suggest the possibility that the inhibition of cell adhesion between UV-B-irradiated Sa target cells and alloreactive CTL is due to the impaired mobility of cell surface antigens which will affect the early process of cell-mediated cytolysis.

Cell Communication↗