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Biomedical subjects

M Okada

Publications and source records attributed to M Okada.

At least 721 records · Page 40Linked to original sources
PubMed1996

Right ventricular ejection fraction in the preoperative risk evaluation of candidates for pulmonary resection.

The major determinants of postoperative morbidity and mortality after lung resection are the physiologic and functional statuses of the pulmonary and cardiac systems. In our previous study, serial measurements of right ventricular performance after pulmonary resection demonstrated significant right ventricular dysfunction in the postoperative period. This study evaluates the preoperative measurement of right ventricular ejection fraction as a predictor of postoperative complications. In addition to conventional cardiopulmonary functional tests, right ventricular function was assessed with a thermodilution technique at rest and during exercise in 18 patients before and 3 weeks after lobectomy or pneumonectomy. The patients were grouped according to severity of right ventricular functional defect: right ventricular ejection fraction of at least 45% (group Ia, n = 8), right ventricular ejection fraction less than 45% (group Ib, n = 10), exercise-induced increases in right ventricular ejection fraction (group IIa, n = 8), and exercise-induced decreases in right ventricular ejection fraction (group IIb, n = 10). Postoperative cardiopulmonary morbidity was recorded for two patients (25%) in group Ia, three patients (30%) in group Ib, no patients (0%) in group IIa, and five patients (50%) in group IIb. Postoperative hospital stay was 28.9 +/- 8.5 days in group Ia, 29.9 +/- 20.2 days in group Ib, 19.4 +/- 8.0 days in group IIa, and 37.5 +/- 15.9 days in group IIb (p < 0.05, group IIa vs group IIb). Although resection-induced changes in forced expiratory volume in 1 second did not differ significantly between group Ia and group Ib, these values appeared to be increased in groups IIa (not statistically significant) and IIb (significantly, p < 0.05). The measured postoperative values of forced expiratory volume in 1 second and vital capacity were significantly higher than the predicted postoperative values (p < 0.05) in group IIa, but not in groups Ia, Ib, and IIb. We conclude that evaluation of right ventricular performance is useful in determining which patients are at increased risk for medical complications after lung resection. Exercise-induced change in right ventricular ejection fraction may be a better indicator of high risk among candidates for pulmonary resection than the absolute value of this parameter.

Aged↗
PubMed1996

Second transplantation with CD34+ bone marrow cells selected from a two-loci HLA-mismatched sibling for a patient with chronic myeloid leukaemia.

A 43-year-old man with chronic myeloid leukaemia underwent a second transplant with CD34+ bone marrow cells selected from his two-loci HLA-mismatched sibling after rejection of the first graft from an HLA-matched unrelated donor. By immunomagnetic positive selection, CD34+ marrow cells at 0.95 x 10(6)/kg with 97% purity and CD3+ T lymphocytes at 1.3 x 10(4)/kg were collected and transplanted. Engraftment was confirmed to be of CD34+ cell-donor origin. The patient developed only grade I acute graft-versus-host disease (GVHD) and no chronic GVHD to date. These observations suggest that allogeneic CD34+ bone marrow cells are capable of reconstituting haemopoiesis and that CD34+ selection could be applicable to T-cell depletion.

Adult↗
PubMed1996

Human monoclonal rheumatoid factors augment arthritis in mice by the activation of T cells.

In order to investigate the in vivo role of rheumatoid factor (RF), the effects of the administration of human monoclonal (m) IgM-RF and IgG-RF on the development of arthritis in mice were examined. The administration of human mRFs into mice immunized with type II collagen (CII) markedly enhanced the clinical score and paw swelling. The severity of arthritic joint disease with a marked infiltration of lymphoid cells, proliferation of synovial membrane, pannus formation and destruction of articular cartilage was significantly enhanced in both groups receiving RF (RF-enhanced arthritis). Skin ulcers were also observed in some of these RF-enhanced arthritis mice, whereas no such signs were observed in CII-immunized mice without mRFs. Both IgM-RF and IgG-RF increased CII-specific IgG antibodies in circulation, and the severity of arthritis correlated with the production of high titres of anti-CII antibodies. In vivo treatment of RF-enhanced arthritis mice with an anti-CD4 MoAb or an anti-CD8 MoAb inhibited the induction and progression of arthritis in these mice. Administration of RF to severe combined immunodeficient (SCID) mice with arthritis developed by the transfer of spleen cells from CII-immunized mice, prolonged the arthritis and enhanced the severity. This murine model of RF-enhanced arthritis may provide a useful tool for analysing the pathogenesis of rheumatoid arthritis in RF-positive patients.

Adoptive Transfer↗
PubMed1996

Two mechanisms for platelet-mediated killing of tumour cells: one cyclo-oxygenase dependent and the other nitric oxide dependent.

We have tried to identify the cytotoxic effectors in platelet-mediated tumour cell killing, using two tumour cell lines K562 (a chronic myelogenic leukaemic cell line) and LU99A (a lung cancer cell line), which are both sensitive to platelet cytotoxicity. Cyclo-oxygenase inhibitors, acetylsalicylic acid (ASA) and indomethacin, effectively inhibited the platelet-mediated killing of K562 cells, but not that of LU99A cells. In contrast, inhibitors of the nitric oxide (NO) pathway. NG-nitro-1-arginine (L-NA), haemoglobin and methylene blue, reduced the cytotoxic activity of platelets against LU99A, but not against K562. Synthetic analogues of platelet cyclo-oxygenase products thromboxane A2/ prostaglandin H2(TXA2/PGH2) exerted cytotoxicity against K562 cells but not against LU99A cells. Electron microscopic study showed that TXA2/PGH2 analogues induced bleb formation and disruption of the plasma membrane of K562 cells. K562 cells enhanced the production of TXA2 by platelets, as inferred from the accumulation of thromboxane B2 (TXB2), a spontaneous hydrolysis product of TXA2. LU99A cells had no such effects. These results indicate that platelets kill these two tumour cell lines through different mechanisms. In K562, the cyclooxygenase products TXA2/PGH2 possibly play a significant role but in LU99A the NO pathway seems to be involved.

Aspirin↗
PubMed1996

Enhancement of CD3-mediated thymocyte apoptosis by the cross-linkage of heat-stable antigen.

Heat-stable antigen (HSA) is a murine differentiating antigen that is expressed on both CD4-CD8- double-negative and CD4+CD8+ double-positive thymocytes but not CD4+ or CD8+ single-positive thymocytes. Effects of anti-HSA monoclonal antibody, R13, on thymocyte apoptosis induced by various stimulations were investigated by a single-cell suspension culture system. Immobilized R13 enhanced the CD3-mediated DNA fragmentation and killing of thymocytes but not the dexamethasone-induced or phorbol myristate acetate-induced killing of thymocytes. Immobilized R13 by itself could not induce thymocyte apoptosis. Soluble R13 enhanced CD3-mediated apoptosis when HSA and T-cell receptor (TCR)/CD3 were co-cross-linked by a cross-reactive secondary antibody. Even without the cross-reactive secondary antibody, soluble R13 enhanced CD3-mediated apoptosis, although a greater than 100-fold increase in the amount of R13 was needed to give a similar enhancement compared with immobilized R13. Neither R13 by itself nor R13 plus secondary antibody induced cytosolic calcium influx, whereas R13 enhanced CD3-mediated cytosolic calcium increase. These results suggest a functional role of HSA in promoting the activation-induced apoptosis of thymocytes and the involvement of HSA in negative selection.

Animals↗
PubMed1996

Response of renal nerve activity to high NaCl food intake in dogs with chronic bile duct ligation.

Hepatic sensory systems are thought to play an important role in the response of renal nerve activity and natriuresis to oral NaCl load. In this study, responses of renal nerve activity and urinary Na+ and Cl- excretions to a high-NaCl food intake (20 g/kg boiled rice containing 0.4 g/kg NaCl) were examined in sham-operated dogs (n = 12) and dogs with chronic bile duct ligation (CBDL; n = 10). In sham-operated dogs, renal nerve activity gradually decreased and reached minimal value (50% +/- 7% of the control value) at 100 minutes after the high-NaCl food intake and remained depressed until 4 hours after the food intake. Of the orally administered sodium and chloride, 27% +/- 5% and 23% +/- 6% were excreted over the following 4 hours, respectively. In CBDL dogs, the decrease in renal nerve activity induced by the high-NaCl food was completely abolished and only 4% +/- 1% of the loaded Na+ and 3% +/- 2% of the loaded Cl- were excreted. Furthermore, liver tissue norepinephrine concentration in CBDL dogs decreased to 21% of that of sham-operated dogs. These results suggest that (1) In CBDL dogs, the decrease in renal nerve activity induced by a high-NaCl food is completely abolished, probably because of the impairment of hepatic neural regulation. (2) The lack of renal nerve response may contribute, at least in part, to the abnormalities in body fluid homeostasis in cirrhosis.

Animals↗
PubMed1996

Magnetic resonance relaxation time in evaluating the cyst fluid characteristics of endometrioma.

To determine whether the cyst fluid characteristics of endometrioma can be evaluated by magnetic resonance imaging (MRI), 36 endometriomas obtained from 24 patients (age range 21-43 years; mean 34 years) were studied. MRI was performed < 2 weeks before laparoscopy or laparotomy. Comparative studies of the density and concentration of iron in the endometrioma and the signal intensity (SI) of MRI [calculated relaxation time T1 value, calculated relaxation time T2 value, signal intensity on a T1-weighted image (T1SI) and on a T2-weighted image (T2SI) of the cyst; T1SI/signal intensity of the gluteus maximus muscle (MSI), and T2SI/MSI of the cyst] were performed. The density of the cyst fluid and its iron concentration were found to be directly proportional. There was a significant relationship between the concentration of iron and the T2SI, T2SI/MI and calculated T2 values. In particular, the concentration of iron and the ration of T2SI/ MSI were inversely proportional. Therefore, T2SI/MSI reflected the concentration of iron in endometriomas without recourse to measurement of the calculated T2 value, which suggests that the MRI and T2 signal intensity may be useful for evaluating the cyst fluid characteristics of endometriomas.

Adult↗
PubMed1996

Prognostic application of magnetic resonance imaging in patients with endometriomas treated with gonadotrophin-releasing hormone analogue.

We evaluated the usefulness of magnetic resonance imaging (MRI) for assessing the response of patients with endometriomas to medical therapy. MRI was performed before and after treatment in 20 consecutive patients with at least one endometrioma with a maximal diameter >10 mm diagnosed by laparoscopy who received 900 microg of buserelin acetate daily for 6 months. Patients were categorized as good responders (group I, n = 13) and poor responders (group II, n = 7) depending on the results of a third-look laparoscopy performed 6 months after treatment. We determined the ratio of the signal intensity (SI) of the endometrioma to the SI of the gluteus maximus muscle on T2-weighted images [T2SI/M (muscle) SI] and the volume of the endometrium. The volume decreased by >50% in 61.5% of the good-response group and 57.1% of the poor-response group. There was no significant difference between the two groups. The T2SI/MSI decreased in 12 of 13 patients in group I but in only one of seven patients in group II, a significant difference (P < 0.05) between the two groups. In the good-response group, there was a positive linear correlation between the decrease in the volume of the endometrioma and the decrease in the T2SI/MSI after treatment (r = 0. 561, P < 0.05). Therefore, the T2SI/MSI determined from MR images may be useful in assessing the therapeutic response of patients with endometriomas.

Adult↗
PubMed1996

Triple paraneoplastic syndrome of hypercalcemia, leukocytosis and cachexia in two human tumor xenografts in nude mice.

Nude mice bearing the human oral cavity carcinoma cell line OCC-1, and the lung cancer cell line LC-1, developed a triple paraneoplastic syndrome consisting of hypercalcemia, cachexia and leukocytosis. All of these abnormalities disappeared rapidly after surgical resection of the tumors, suggesting their ectopic humoral nature. Search for the factors responsible for the respective abnormalities revealed that the production of parathyroid hormone-related protein and colony-stimulating factors (CSFs), mainly granulocyte-CSF, by the tumors could explain the hypercalcemia and leukocytosis, respectively. With regard to the severe cachexia, the production of two cachexia-associated cytokines, interleukin-6 and leukemia inhibitory factor, was able to explain the syndrome in OCC-1 bearing nude mice; however, the factor responsible in LC-1 bearing nude mice could not be identified. The triple paraneoplastic syndrome that developed in these two animal models could be explained partly by concomitant production of the peptide hormone and cytokines by cancer cells. These animal models may be very useful for the evaluation of diagnostic and therapeutic modalities for humoral abnormalities.

Animals↗
PubMed1996

Magnesium ion augmentation of inhibitory effects of adenosine on dopamine release in the rat striatum.

The effects of adenosine and magnesium ion (Mg2+) on striatal dopamine release were studied in awake rats by in vivo microdialysis. The mean striatal basal levels of dopamine release at Mg2+ free perfusate were 56.95 +/- 5.30 fmol/sample (for 20 min). By varying the Mg2+ levels in perfusate from 0 mmol/L to 1, 10 or 40 mmol/L, the dopamine release was inhibited by Mg2+ in a level-dependent manner. Perfusion with modified Ringer's solution containing zero Mg2+ and from 5 to 50 mumol/L adenosine, non-selective adenosine agonist, as well as 0.1 mumol/L 2-chloro-N6-cyclopentyladenosine (CCPA), selective adenosine A1 agonist, showed no effect on dopamine release. However, from 5 to 50 mumol/L adenosine and from 0.1 to 1 mumol/L CCPA plus Mg2+ (1 and 40 mumol/L) perfusion decreased the dopamine release. This inhibitory effect of adenosine and CCPA on striatal dopamine release was enhanced by an increase in extracellular Mg2+ levels. Levels of 50 mumol/L of 8-cyclopentyl-1,3-dimethylxanthine (CPT), a selective adenosine A1 receptor antagonist, in perfusate increased the dopamine release under conditions both with and without Mg2+. This stimulatory effect of CPT on striatal dopamine release was reduced by an increase in extracellular Mg2+ levels. As a result, CPT antagonized the inhibitory effects of adenosine and CCPA on dopamine release under conditions of the presence and absence of Mg2+. These results suggest that the inhibition of striatal dopamine release by adenosine was mediated by adenosine A1 receptor. This inhibition was intensified by Mg2+. This study also revealed that the concentrations of Mg2+, which ranged from physiological to supraphysiological, reduced the striatal dopamine release; furthermore it was found that the physiological concentration of Mg2+ potentiated the effects of adenosine agonists, but inhibited adenosine antagonist. Thus, the present study, using in vivo microdialysis preparations, suggests Mg2+ inhibits the calcium ion channels and enhances the adenosinergic function in the central nervous system.

Adenosine↗
PubMed1996

Dysplasia in ulcerative colitis: is radiography adequate for diagnosis?

PURPOSE: To determine to usefulness of barium enema examination in detecting dysplasia in patients with ulcerative colitis. MATERIALS AND METHODS: Radiographic findings of 22 areas of dysplasia in 10 patients (seven men, three women; aged 34-81 years at diagnosis) were reviewed. Serial changes in radiographic features of four areas of dysplasia in three patients were retrospectively investigated. RESULTS: Fourteen of 22 areas of dysplasia were shown on radiographs. Dysplasia in the rectum or sigmoid colon was depicted less frequently than that in other segments of the colon. Radiographic features were classified as obvious nodular protrusions (seven lesions), irregular mucosa (five lesions), or nodular protrusions with irregular mucosa (two lesions). Six of the seven areas of dysplasia shown as irregular mucosa were accompanied by minute spiculations in the margin of the colonic lumen. There was no correlation between radiologic features and histologic grade of dysplasia. CONCLUSION: Barium enema examination may be used as a complementary method of cancer surveillance with endoscopy. These methods show about two-thirds of lesions associated with dysplasia.

Adult↗
PubMed1996

Mobility of hindlimb joints in Japanese macaques (Macaca fuscata) as influenced by biarticular musculature.

Joint mobility is a critical issue in the analysis of locomotor adaptation. Here we have attempted precise measurements of the range of extension/flexion of the hip, knee, and ankle joints of Japanese macaques by using fresh cadavers and devising an effective method to fixate the proximal segment. Severance of biarticular muscles revealed restrictions in mobility of as much as 10-25% caused by these muscles. However, incidences of an incomplete removal of the restriction through severance suggest a contribution of cutaneous tissues to the restriction. The mobility ranges determined by this method were compared with the joint motion of Japanese macaques during actual locomotion.

Animals↗
PubMed1996

Cardiac output measurement by thoracic electrical bioimpedance in a patient with ovarian hyperstimulation syndrome.

A 31-year-old woman developed severe ovarian hyperstimulation syndrome (OHSS) after exogenous gonadotropin stimulation for an in vitro fertilization program. Because of refusal of invasive monitoring, thoracic electrical bioimpedance (TEB) was performed to evaluate cardiac function and volume status. TEB pointed out decreased cardiac output (CO: 4.23 liters/min), cardiac index (CI: 2.63) and stroke volume (SV: 57.5 ml/beat). Serial monitoring of hemodynamic variables was then performed. After the data were obtained, fluid management was performed, and the patient recovered from abnormal homeostasis in 3 days. The hemodynamic variables returned to the normal range (CO: 6.85 liters/min, CI: 4.25, SV: 100.5 ml/beat) within the first 24 h. There were no complications such as life-threatening multiple organ failure. We discuss the usefulness of TEB for the fluid management of severe OHSS, as well as its implications.

Adult↗
PubMed1996

Studies on the detection of small endometrial implants by magnetic resonance imaging using a fat saturation technique.

To assess the usefulness of fat-saturated magnetic resonance (MR) imaging in detecting small endometrial implants, 258 pigmented lesions of endometriosis from 80 consecutive patients with histopathologically diagnosed pelvic endometriosis were compared using fat-saturated and conventional MR imaging. MR imaging was performed with a 1.5-tesla superconducting magnet with spin echo T1-, T2-, and fat-saturated T1-weighted images. Both conventional MR images and fat-saturated MR images permitted identification of almost all endometriomas > 10 mm in diameter. With conventional MR imaging, 29 endometrial implants measuring < 10 mm in diameter were detected. One hundred and seven lesions were detected by fat-saturated MR imaging. However, conventional MR images demonstrated only 4 lesions among these 111 small endometrial implants that measured < 5 mm in diameter. The addition of fat-saturated MR imaging increased the detection rate to 55 of 111 lesions. Fat-saturated MR imaging can, therefore, be useful in detecting small endometrial implants.

Adult↗
PubMed1996

Surgical treatment of refractory venous stasis ulcer due to a severe impairment of calf muscle pump function: evaluation by air plethysmography. A case report.

The authors encountered a forty-nine-year-old man with a lower limb ulcer refractory to intensive conservative therapy. No varicose vein was found anywhere, and the usual phlebographies and foot venous pressure measurement failed to diagnose it as a venous stasis ulcer. A direct phlebography method developed by the authors, in which a thin catheter is inserted into the deep vein, disclosed a reflux of the popliteal vein or a deep muscle branch from which an incompetent perforator arose toward the superficial vein above the ulcer. Air plethysmography (APG) showed a severe impairment of the calf muscle pump function. He underwent a subfascial ligation of two incompetent perforators together with a stripping of the great saphenous vein passing under the ulcer. Postoperatively, this ulcer was cured in an early phase, and the calf muscle pump function showed improvement in the APG.

Hemodynamics↗
PubMed1996

A new method for permeabilization of the plasma membrane of cultured mammalian cells. IV. Structural requirement for high molecular weight polymers for potentiation of bleomycin cytotoxicity toward mammalian cells under conditions of vortex-stirring.

As we previously reported, the cytotoxicity of bleomycin (BLM) toward cultured mammalian cells was extraordinarily potentiated when the cells and BLM were vortex-stirred for a few seconds in the presence of high molecular weight polyacrylic acid (PAA). Cationic and nonionic polymers could not take the place of PAA in potentiating BLM cytotoxicity. The present study revealed that potentiation was sharply dependent on the molecular weight of PAA and a molecular weight of over 10(6) daltons seemed to be required. Copolymers of acrylic acid (AA) and acrylamide showed some potentiation which was relative to their AA content. It is worth noting that another type of anionic polymer, polymethacrylic acid, did not show any potentiating capacity at all. Polyacrylic sulfonate derivative showed a marginal capacity. The structural requirement for high molecular weight polymers for potentiation of BLM cytotoxicity was demonstrated by the increased uptake of Lucifer Yellow, a non-permeant material. In addition, the ability of permeabilization was not correlated with kinematic viscosity of anionic polymers.

Animals↗