Biomedical subjects

S Nagashima

Publications and source records attributed to S Nagashima.

At least 19 recordsLinked to original sources

PubMed1999

Comparative antiplatelet effects of aspirin, vapiprost and GR144053, a GPIIb/IIIa antagonist, with a special reference to the role of platelet microaggregates.

Microthrombi produced have a potential to form larger thrombi, leading to vascular occlusions. Recently, a new device to easily detect microaggregates using laser-light scattering (LS) has been developed. We adopted this device to comparatively evaluate the inhibitory effects of aspirin (1,3 or 10 mg kg(-1)), vapiprost (0.3, 1 or 3 mg kg(-1)) or GR144053 (0.1, 0.3 or 1 mg kg(-1)) on ex vivo aggregation of hamster platelets in relation to their in vivo antithrombotic effects. A transluminal thrombus was produced in the hamster femoral artery by the photochemical reaction. Each compound was injected i.v. as a bolus 10 min prior to the reaction, showing a dose-dependent antithrombotic effect, i.e. they prolonged the time before the artery occluded. At that time cyclic flow reductions occurred more marked when aspirin or vapiprost was given. At the end of experiments, blood was collected to evaluate the platelet aggregation using both the new LS device and the conventional optical density (OD) method. Many more small aggregates were still formed when the highest dose of aspirin or vapiprost was used as compared with that of GR144053, although suppression of the platelet aggregation using the OD method, prolongation of the occlusion time and the bleeding time were quite similar. In conclusion, a GPIIb/IIIa antagonist markedly suppressed the microthrombi and reduced the cyclic flow reduction. This further indicates the importance of small aggregates as triggers of thrombosis and shows that prevention of their formation may result in improved vascular patency after thrombotic insult.

Animals↗

PubMed1999

Ankle arthrodesis in rheumatoid arthritis using an intramedullary nail with fins.

We describe an intramedullary nail with fin-like longitudinal ridges that we have developed for arthrodesis of the ankle in rheumatoid arthritis. Four fins with sharp tips were attached to the distal part of a cylindrical nail to stabilize the tibiotalar and subtalar joints. We used this nail in 15 feet of 15 patients with rheumatoid arthritis who were followed for an average of 34.9 months. Postsurgery, 13 patients were allowed to bear weight immediately, as tolerated, without immobilization. By 3 weeks, these patients were able to bear weight fully. Solid fusion of the ankle joint in an acceptable position and good clinical results were obtained in all patients. The only complications were two cases of delayed wound-healing.

Adult↗

PubMed1998

Characterization of fetal serum 5'-nucleotide phosphodiesterase: a novel function as a platelet aggregation inhibitor in fetal circulation.

The study was performed to indicate the ADPase activity of 5'-nucleotide phosphodiesterase (PDEase) from human umbilical cord blood serum and demonstrates the effect of this enzyme on ADP-induced platelet aggregation. The PDEase was purified by using p-nitrophenyl-5'-TMP as a substrate. The PDEase had a molecular weight of 128,000 daltons, and activity of 103 nmol/min/mg protein. The PDEase activity was inhibited by 5'-AMP, ADP, ATP. But 2'-AMP, 3'-AMP, 3':5' cAMP, and adenosine had no inhibiting effects. Kinetic analysis indicated that ADP was a competitive inhibitor with a Ki value of 4.05x10(-5) M. The enzyme was markedly inhibited by 1 mM EDTA. The ADPase activity of the PDEase was 7.79 nmol/min/mg protein. The hydrolized products of ADP by the PDE ase were AMP and phosphoric acid. The platelet aggregation by ADP was inhibited by the addition of the PDEase in the platelet-rich plasma.

Adenosine Diphosphate↗

PubMed1998

Stable transduction of the interleukin-2 gene into human natural killer cell lines and their phenotypic and functional characterization in vitro and in vivo.

A variety of strategies have been attempted in the past to stably transduce natural killer (NK) cells with cytokine or other cellular genes. Here, we demonstrate the successful delivery of the interleukin-2 (IL-2) gene into two human NK cell lines, IL-2-dependent NK-92 and IL-2-independent YT, by retroviral transduction. An MuLV-based retroviral vector expressing human IL-2 and neor markers from a polycistronic message was constructed and transduced into a CRIP packaging cell line. By coincubation of NK cells with monolayers of CRIP cells or by using retrovirus-containing supernatants in a flow-through method, 10% to 20% of NK cells were stably transduced. Upon selection in the presence of increasing G418 concentrations, transduced NK cells were able to proliferate independently of IL-2 for more than 5 months and to secrete up to 5.5 ng/10(6) cells/24 h of IL-2. IL-2 gene-transduced NK-92 cells had an in vitro cytotoxicity against tumor targets that was significantly higher than that of parental cells and secreted interferon gamma (IFNgamma) and tumor necrosis factor alpha (TNFalpha) in addition to IL-2. Moreover, the in vivo antitumor activity of IL-2 gene-transduced NK-92 cells against established 3-day liver metastases in mice was greater than that of parental nontransduced NK cells. Stable expression of the IL-2 transgene in NK cells improved their therapeutic potential in tumor-bearing hosts. Thus, transduced NK cells secreted sufficient quantities of bioactive IL-2 to proliferate in vitro and mediated the antitumor effects both in vitro and in vivo in the absence of exogenous IL-2. These results suggest that genetic modification of NK cells ex vivo could be useful for clinical cancer therapy in the future.

Animals↗

PubMed1998

Size Dependence of Polymer Composition in the Surface Layer of Poly(acrylamide-co-acrylic acid) Hydrogel Microspheres

Poly(acrylamide-co-acrylic acid) hydrogel microspheres of four different average sizes were prepared using a membrane emulsification technique. These four kinds of microspheres had average diameters of 1.35, 2.33, 3.09, and 7.43 &mgr;m in distilled water and were all fairly monodisperse. Their surface properties were studied by measuring the electrophoretic mobility of the microspheres. The mobility values were negative at pH 7.4 with the ionic strengths between 0.005 and 0.154 at 25°C. More negative mobility values were obtained with smaller microspheres than the larger ones. By analyzing the data with an electrokinetic theory for "soft" surfaces, it was found that smaller microspheres have higher surface charge density than the larger ones, although all kinds of microspheres were prepared from monomer solutions with the same monomer composition. The observed size dependence of the electrophoretic mobility suggests that copolymerization of acrylamide monomers and acrylic acid monomers does not proceed homogeneously within a microsphere. That is, charged acrylic acid monomers have a tendency to be localized in the microsphere core region, whereby the surface region of microspheres becomes poor in charges, reducing the mobility of larger microspheres. This is not the case for smaller microspheres, so that their mobility becomes more negative. Copyright 1998 Academic Press. Copyright 1998Academic Press

Journal Article↗

PubMed1998

Adenosine A1-receptor occupancy predicts A1-receptor antagonist effects of N-0861.

OBJECTIVE: To evaluate the relationship between dose of N-0861 ([+/-]N6-endo-norbornan-2-yl-9-methyladenine), N-0861 plasma concentrations, and antagonism of adenosine-induced slowing of atrioventricular nodal conduction and to evaluate A1-receptor occupancy by antagonist present in plasma of subjects after administration of N-0861 to determine A1-selectivity of these effects. METHODS: The study was conducted in patients undergoing a clinically indicated electrophysiology study to evaluate atrioventricular nodal conduction. Nineteen subjects were enrolled in the study and received adenosine (60 to 140 microg/kg) before or during a bolus dose and maintenance infusion of specific doses of N-0861. Adenosine-induced slowing of atrioventricular nodal conduction was determined by measuring A-H intervals on the intracardiac electrocardiograms. Plasma concentrations of N-0861 were determined with an HPLC method. A1-Receptor occupancy by antagonist present in plasma from identical time points was determined with use of a radioreceptor assay. RESULTS: A linear relationship was shown between plasma concentration and dose of N-0861. A-H interval lengthening by 60 microg/kg adenosine was reduced by administration of N-0861. A linear relationship was observed between A1 occupancy and N-0861 concentration and between occupancy and antagonism of adenosine-induced A-H prolongation. CONCLUSION: The results suggest that the effect of N-0861 on antagonism of adenosine-induced prolongation of A-H interval, at the doses used in this study, were the result of effects at the A1 receptor.

Adenine↗

PubMed1998

Novel non-heme iron center of nitrile hydratase with a claw setting of oxygen atoms.

The iron-containing nitrile hydratase (NHase) is a photoreactive enzyme that is inactivated in the dark because of persistent association with NO and activated by photo-dissociation of NO. The crystal structure at 1.7 A resolution and mass spectrometry revealed the structure of the non-heme iron catalytic center in the nitrosylated state. Two Cys residues coordinated to the iron were post-translationally modified to Cys-sulfenic and -sulfinic acids. Together with another oxygen atom of the Ser ligand, these modifications induced a claw setting of oxygen atoms capturing an NO molecule. This unprecedented structure is likely to enable the photo-regulation of NHase and will provide an excellent model for designing photo-controllable chelate complexes and, ultimately, proteins.

Bacterial Proteins↗

PubMed1998

Pharmacokinetics and safety of a new parenteral carbapenem antibiotic, biapenem (L-627), in elderly subjects.

The pharmacokinetics and tolerability of a new parenteral carbapenem antibiotic, biapenem (L-627), were studied in healthy elderly volunteers aged 65 to 74 years (71.6 +/- 2.7 years [mean +/- standard deviation], n = 5; group B) and > or = 75 years (77.8 +/- 1.9 years, n = 5; group C), following single intravenous doses (300 and 600 mg), and compared with those of healthy young male volunteers aged 20 to 29 years (23.0 +/- 3.5 years, n = 5; group A). The agent was well tolerated in all three age groups. Serial blood and urine samples were analyzed for biapenem to obtain key pharmacokinetic parameters by both two-compartment model-dependent and -independent methods. The maximum plasma concentration and area under plasma concentration-versus-time curve (AUC) increased in proportion to the dose in all three groups. Statistically significant age-related effects for AUC, total body clearance, and renal clearance (CLR) were found, while elimination half-life (t1/2 beta) and percent cumulative recovery from urine of unchanged drug (% UR) remained unaltered (t1/2 beta, 1.51 +/- 0.42 [300 mg] and 2.19 +/- 0.64 [600 mg] h [group A], 1.82 +/- 1.14 and 1.45 +/- 0.36 h [group B], and 1.75 +/- 0.23 and 1.59 +/- 0.18 h [group C]; % UR, 52.6% +/- 3.0% [300 mg] and 53.1% +/- 5.1% [600 mg] [group A], 46.7% +/- 7.4% and 53.0% +/- 4.8% [group B], and 50.1% +/- 5.2% and 47.1% +/- 7.6% [group C]). A significant linear correlation was observed between the CLR of biapenem and creatinine clearance at the dose of 300 mg but not at 600 mg. The steady-state volume of distribution tended to be decreased with age, although not significantly. Therefore, the age-related changes in parameters of biapenem described above were attributable to the combination of decreased lean body mass and lowered renal function of the elderly subjects. However, the magnitude of those changes does not necessitate dosage adjustment in elderly patients with normal renal function for their age.

Adult↗

PubMed1998

Pharmacokinetic study of an oral cephalosporin, cefdinir, in hemodialysis patients.

The pharmacokinetics of cefdinir were investigated in six hemodialysis patients. For the present study, two tests were carried out, one with 4 h of hemodialysis and the other without hemodialysis. Cefdinir was given orally to each patient in a dose of 100 mg, and blood was collected serially for 48 h after dosing in the test without dialysis and for 72 h in the test with dialysis. In the test without dialysis, the maximum plasma concentration (Cmax) was 2.36 +/- 0.53 micrograms/ml (mean +/- standard deviation) and the time to Cmax was 9.00 +/- 2.45 h. The terminal elimination half-life (t1/2) and area under the concentration-time curve (AUC) were 16.95 +/- 1.20 h and 69.05 +/- 14.84 micrograms.h/ml, respectively. In the test with dialysis, t1/2 during hemodialysis decreased approximately to one-sixth of that obtained in the test without dialysis, although t1/2 in the latter elimination phase did not differ from that in the nondialysis test. AUC was reduced to 43% of that in the test without dialysis. The fractional removal of cefdinir by hemodialysis was 61%. These findings indicate that clearance of cefdinir is prolonged in patients with renal failure, and cefdinir is well removed by introduction of hemodialysis, although t1/2 (during hemodialysis) and AUC were two and eight times higher than the data previously reported for healthy volunteers, respectively. The pharmacokinetic data suggest that 100 mg of oral cefdinir once a day would result in a sufficient concentration in plasma in hemodialysis patients, but this remains to be confirmed by multiple-dose studies.

Administration, Oral↗

PubMed1998

Hypotensive effects of an angiotensin II type 1 receptor antagonist differ between exercised and sedentary rats aged from 4 to 19 weeks.

The hypotensive effects of an angiotensin II type 1 receptor antagonist TCV-116 were accelerated by swimming training in the early period of chronic administration in young rats. In the latter period, however, a severe decrease in blood pressure that appeared during long-term administration of TCV-116 was prevented by swimming training. Therefore exercise may contribute to the stabilization of blood pressure in young rats treated with TCV-116.

Angiotensin Receptor Antagonists↗

PubMed1998

Human tumor antigen-specific T lymphocytes and interleukin-2-activated natural killer cells: comparisons of antitumor effects in vitro and in vivo.

Human antitumor effector cells include class I major histocompatibility complex (MHC)-restricted T cells and non-MHC-restricted natural killer (NK) cells. These two types of effector cells have not been directly compared for the ability to eliminate tumor cell targets. Here, we compare in vitro and in vivo antitumor functions of two human T-cell lines specific for a shared tumor antigen to the antitumor functions of A-NK cells, a subset of IL-2-activated NK cells. Human squamous cell carcinoma of the head and neck cell lines cultured in suspensions or as spheroids or tumor xenografts established in nude mice were used to evaluate antitumor functions of IL-2-activated and expanded T and NK effector cells in various assays, both in vitro and in vivo. Both tumor cell targets, PCI-13 and OSC-19, expressed class I and II MHC antigens after IFN-gamma pretreatment, gave rise to tumors upon injection into immunosuppressed nude mice, and were resistant to lysis by resting NK cells but sensitive to lysis mediated by A-NK cells or HLA-A2-restricted T-cell lines specific for a shared squamous cell carcinoma of the head and neck antigen. No significant differences were observed in the ability of A-NK cells or tumor-specific T cells to bind to tumor cell monolayers or to enter into spheroids. However, A-NK cells mediated significantly higher killing than tumor-specific CD8+ T cells in 4-h 51Cr-release assays (a measure of cell membrane damage and necrosis), 1-h [3H]thymidine-release assays (a measure of DNA fragmentation and apoptosis), and in terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assays (a measure of apoptosis). In contrast, CD8+ T cells were consistently more effective than A-NK cells in inducing growth inhibition of tumor cells in 24-h MTT assays. In the presence of tumor-specific antibodies, A-NK cell binding, entry into spheroids, and infiltration into tumor in vivo were significantly increased. In vivo perilesional delivery of effector cells to mice with established tumors indicated that human A-NK cells exert antitumor effects as potent as those of tumor-specific T cells. However, in contrast to tumor-specific T cells, A-NK cells are readily available for cancer therapy, expand rapidly in culture without prior sensitization, and can be armed with antitumor antibodies to increase localization of effector cells to the tumor.

Animals↗

PubMed1997

Structure of the photoreactive iron center of the nitrile hydratase from Rhodococcus sp. N-771. Evidence of a novel post-translational modification in the cysteine ligand.

Nitrile hydratase (NHase) from Rhodococcus sp. N-771 is a photoreactive enzyme that is inactivated by nitrosylation of the non-heme iron center and activated by photodissociation of nitric oxide (NO). To obtain structural information on the iron center, we isolated peptide complexes containing the iron center by proteolysis. When the tryptic digest of the alpha subunit isolated from the inactive form was analyzed by reversed-phase high performance liquid chromatography, the absorbance characteristic of the nitrosylated iron center was observed in the peptide fragment, Asn105-Val-Ile-Val-Cys-Ser-Leu-Cys-Ser-Cys-Thr-Ala-Trp-Pro-Ile-Leu - Gly-Leu-Pro-Pro-Thr-Trp-Tyr-Lys128. The peptide contained 0.79 mol of iron/mol of molecule as well as endogenous NO. Subsequently, by digesting the peptide with thermolysin, carboxypeptidase Y, and leucine aminopeptidase M, we found that the minimum peptide segment required for the nitrosylated iron center is the 11 amino acid residues from alphaIle107 to alphaTrp117. Furthermore, by using mass spectrometry, protein sequence, and amino acid composition analyses, we have shown that the 112th Cys residue of the alpha subunit is post-translationally oxidized to a cysteine-sulfinic acid (Cys-SO2H) in the NHase. These results indicate that the NHase from Rhodococcus sp. N-771 has a novel non-heme iron enzyme containing a cysteine-sulfinic acid in the iron center. Possible ligand residues of the iron center are discussed.

Amino Acid Sequence↗

PubMed1997

Human gastric carcinoma transduced with the IL-2 gene: increased sensitivity to immune effector cells in vitro and in vivo.

We transduced a human gastric carcinoma cell line, HR, with the interleukin 2 (IL-2) gene. Stable HR transfectants secreted nanogram quantities of biologically active IL-2 and had significantly increased expression of IL-2 mRNA relative to that in parental cells. Expression of intracellular IL-2 protein was not quantitatively different in the parental and IL-2 gene-transduced cells, although the former did not secrete IL-2. Surface expression of IL-2 receptors was comparable in the parental and transduced cells at the mRNA or protein levels. Nevertheless, in vitro proliferation of IL-2 gene-transduced HR cells was significantly more rapid than that of parental cells. Both parental and IL-2 gene-transduced HR cells were equally sensitive to lysis by IL-2-activated natural killer (A-NK) cells, as measured in 4 hr 51Cr-release assasys or to apoptosis induced by NK or A-NK cells, assessed in 1 hr 3H-TdR-release assays. In 24 hr MTT assays, however, the IL-2 gene-transduced cells were significantly more sensitive to these effector cells than were parental cells. Upon intrasplenic injection of 5 x 10(6) parental or transduced HR cells into nude mice, liver metastases developed. Metastases of parental HR cells killed the animals in 24 days. In contrast, metastases of the IL-2 gene-transduced HR cells became necrotic by day 14 and were found to be surrounded by murine NK cells and macrophages. Survival of nude mice injected with IL-2 gene-transduced HR cells was significantly prolonged (>50 days) relative to that of mice injected with parental HR. Thus, IL-2 gene-transduced HR cells produced sufficient amounts of functional IL-2 in vivo to be able to recruit to the tumor site and support functions of endogenous cytotoxic immune effector cells, which were responsible for regression of hepatic metastases and significant improvement of survival in these mice.

Animals↗

PubMed1997

Cardiac and hemodynamic effects of TZC-5665, a novel pyridazinone derivative, and its metabolite in humans and dogs.

1. TZC-5665 is a novel pyridazinone derivative with vasodilatory and beta-adrenergic blocking activities and type III phosphodiesterase inhibitory action. 2. In healthy volunteers, TZC-5665 was rapidly absorbed and immediately metabolized. Its main metabolite, M-2, remained at a higher concentration in plasma. Orally administered TZC-5665 reduced end-diastolic left ventricular volume (20.16 ml) and exhibited a tendency to increase ejection fraction (0.04). 3. In dogs, M-2 dose-dependently increased cardiac contractility and reduced both preload and afterload. These effects appeared more potent in the failed heart than in the normal heart. At the same dose (30 micrograms/kg), the effects of M-2 seem to be more potent than those of milrinone. 4. We concluded that TZC-5665 is a useful medication for treating patients with chronic congestive heart failure (CHF) because of the positive inotropic and vasodilating effects due to its active metabolite in addition to its own beta-adrenergic blocking actions.

Adult↗

PubMed1997

Alveolar bone loss in rats infected with a strain of Prevotella intermedia and Fusobacterium nucleatum isolated from a child with prepubertal periodontitis.

Prevotella intermedia and fusobacterium nucleatum are associated with various forms of periodontal disease. The purpose of the present study was to infect the clinical isolates of these periodontopathic bacteria and to induce a significant loss of alveolar bone in specific pathogen-free (SPF) rats in the absence of ligatures. P. intermedia YKD8 and F. nucleatum YKZ5 were isolated from a prepubertal periodontitis patient, while P. gingivalis MWB13 was from a patient with juvenile periodontitis. At first, SPF Sprague-Dawley rats (70 days of age, male) were infected with A. viscosus Ny1R and subsequently superinfected with P. gingivalis MWB13, P. intermedia YKD8, or F. nucleatum YKZ5, respectively. The control group was infected with A. viscosus Ny1R alone. All rats were killed and periodontal bone levels were assessed morphometrically 135 days after the first infection with A. viscosus. P. intermedia YKD8 was recovered frequently from rats, with serum antibody levels remaining highly elevated throughout the experiment. Significant loss of alveolar bone was found in rats infected with P. intermedia YKD8, the virulence of which was equivalent to that of P. gingivalis MWB13. F. nucleatum YKZ5 also induced alveolar bone loss, but not significantly when compared with rats infected with A. viscosus Ny1R alone.

Aggregatibacter actinomycetemcomitans↗

PubMed1997

Bronchial artery aneurysm as a cause of atelectasis.

A 54-year-old nonsmoker female developed atelectasis of the anterior basal segment of the right lower lobe. A non-pulsating endobronchial tumor was observed bronchoscopically obstructing the right basal bronchus. The tumor was confirmed on arteriography to be a saccular aneurysm of the right bronchial artery. The aneurysm was treated with bronchial artery embolization. Bronchial artery aneurysm, without a predisposing disease, is quite rare, but should be considered as an etiological factor of atelectasis.

Aneurysm↗

PubMed1997

Comparison of the results of bilateral total knee arthroplasty with and without patellar replacement for rheumatoid arthritis. A follow-up note.

Simultaneous bilateral total knee arthroplasty was performed in twenty-six patients who had rheumatoid arthritis, and a patellar replacement was performed concurrently in one randomly selected knee in each patient. A lateral retinacular release was performed in all knees. The patients were followed for at least six years (mean, 6.6 years; range, 6.0 to 7.5 years), and the postoperative status of the patients was evaluated with the knee score of The Hospital for Special Surgery. Pain on standing and on ascending or descending stairs as well as tenderness of the patellofemoral joint also were assessed. The over-all score and the individual scores for pain, function, range of motion, muscle strength, flexion contracture, and instability were not significantly different between the knees that had had a patellar replacement and those that had not. However, pain on standing and on ascending or descending stairs as well as tenderness of the patellofemoral joint were only noted in knees that had not had a patellar replacement. These findings suggest that, in order to diminish pain on standing and on using stairs, replacement of the patella during total knee arthroplasty is preferable for patients who have rheumatoid arthritis.

Adult↗

PubMed1996

Nonsecretory apoptotic killing by human NK cells.

We defined a novel constitutive mechanism of cell-mediated cytotoxicity, utilized by nonactivated human peripheral blood NK cells against a variety of tumor cell targets resistant to secretory (i.e., perforin/granzyme-mediated) NK cell killing. Untreated NK cells rapidly induced membrane damage and necrosis in K562 target cells (as determined by 51Cr release assay and confirmed by transmission electron microscopy; TEM), in the absence of DNA fragmentation and apoptosis (as assessed by [3H]thymidine release assay and TEM). Chelation of extracellular Ca2+ or paraformaldehyde fixation completely abrogated NK cell secretory activity and necrotic killing. In contrast, NK cells with either normal or impaired secretion consistently exhibited cytotoxicity against a wide variety of solid tumor cell lines in 1-h [3H]thymidine release, but not in 4-h 51Cr release, assays. Thus, the cytotoxicity was attributable to a nonsecretory, cell membrane-mediated mechanism. It appeared to selectively induce DNA fragmentation and apoptosis without plasma membrane damage and necrosis. This was further demonstrated by a terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay and confirmed by TEM. Among defined populations of immune cells, only NK cells showed an inherent ability to rapidly induce apoptotic death in solid tissue-derived malignant cells. This study demonstrates that NK cells are unique immune cells constitutively endowed with multiple mechanisms of destroying abnormal cells.

Apoptosis↗