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Biomedical subjects

Y Koga

Publications and source records attributed to Y Koga.

At least 253 records · Page 14Linked to original sources
PubMed1994

Proton magnetic resonance spectroscopy of brain tumors: an in vitro study.

The ability of proton magnetic resonance spectroscopy (1H MRS) to diagnose brain tumors was investigated using in vitro high-resolution spectra. Fifty-eight surgically excised samples of brain tumors (12 glioblastomas, 4 anaplastic astrocytomas, 6 astrocytomas, 12 meningiomas, 6 neurinomas, 4 chordomas, 3 craniopharyngiomas, 2 pituitary adenomas, 2 malignant lymphomas, 1 ependymoma, 1 medulloblastoma, and metastatic brain tumors including 3 pulmonary adenocarcinomas, a hepatocellular carcinoma, and a renal cell carcinoma) and 4 nontumorous lobectomized brains were examined by in vitro 1H MRS. N-Acetyl-aspartate was demonstrated in normal tissues but could not be detected in nonneuroectodermal tumors. Total creatine was decreased in all brain tumors in comparison with normal brain tissues, but was relatively higher in neuroectodermal tumors than in other brain tumors. Choline-containing compounds were present in all tumors except craniopharyngioma, and their concentrations were particularly high in a metastatic brain tumor from hepatocellular carcinoma. The concentration of glycine was high in neuroectodermal tumors, whereas that of taurine was high in medulloblastoma, pituitary adenoma, and renal cell carcinoma. Alanine was increased in meningioma, glioma, and pituitary adenoma. Neurinoma had the largest inositol content among the tumors examined. Thus each type of brain tumor exhibited a characteristic MR spectrum. These data suggested that in vivo 1H MRS might provide clinically useful information about tumor metabolism and aid in the differential diagnosis of tumors. Although excellent anatomical localization of tumors can be readily obtained by MR imaging, MRS may provide additional information in cases in which the differential diagnosis of tumors by MR imaging is difficult.

Adolescent↗
PubMed1994

A protease inhibitor, NCO-700, improves the contractile function in stunned canine myocardium.

To explore the role of calcium-dependent protease in the stunned myocardium, open-chest dogs underwent 15 min of left anterior descending coronary artery occlusion followed by 2 h of reperfusion. Dogs received a single bolus intravenous injection of either the protease inhibitor NCO-700 (n = 6) or saline (n = 6) 1 min before reperfusion followed by a 30-min infusion at the same dose. Regional myocardial function was assessed in terms of systolic wall thickening with an epicardial Doppler probe. The two groups exhibited comparable systolic thickening under baseline conditions and similar degrees of dyskinesis during occlusion. After reperfusion, recovery of contractile function, expressed as a percentage of the baseline value, was significantly greater in NCO-700-treated dogs as than in control dogs: -14.3 +/- 10.6 vs -48.9 +/- 7.2 (p < 0.05) at 15 min, 10.8 +/- 10.3 vs -31.1 +/- 9.0 (p < 0.05) at 30 min, 42.5 +/- 10.1 vs -16.4 +/- 9.1 (p < 0.005) at 1 h, and 47.5 +/- 8.3 vs -14.9 +/- 9.4 (p < 0.001) at 2 h. The data suggest that the protease inhibitor markedly improved contractile function in stunned myocardium by inhibiting intracellular protease activity.

Animals↗
PubMed1994

Phosphorylethanolamine content of human brain tumors.

Phosphorylethanolamine (PEA) is the major component of the phosphomonoester peak detected by phosphorus-31 magnetic resonance spectroscopy, but the absolute concentration has not been determined. This study measured the PEA concentration in biopsy specimens of brain tumors and lobectomized cerebral cortex using high-performance liquid chromatography. The concentration of PEA was 118.5 +/- 10.0 mumol/100 g wet wt in cortex, and was significantly higher in malignant gliomas, metastatic pulmonary adenocarcinoma, and neurinoma. The concentration of PEA was especially high in pituitary adenoma, malignant lymphoma, and medulloblastoma.

Brain Neoplasms↗
PubMed1994

Soluble form of P-selectin in patients with acute myocardial infarction.

BACKGROUND: P-selectin, an integral membrane glycoprotein of platelets and endothelial cells, is rapidly redistributed to the cell surface after cellular activation. The soluble form of P-selectin has been shown to be present in people with normal circulation. The purpose of the present study was therefore to examine the soluble form of P-selectin in patients with acute myocardial infarction (AMI). METHODS: Whole blood was obtained from nine patients with AMI and from 10 volunteers who made up the control group. Plasma concentrations of the soluble form of P-selectin were examined with a monoclonal antibody-based enzyme immunoassay. RESULTS: Plasma P-selectin levels in control volunteers were 178 +/- 44 ng/ml. In patients with AMI, plasma P-selectin levels on days 1, 2 and 3 were 743 +/- 374, 627 +/- 267, and 588 +/- 223 ng/ml, respectively (P < 0.001)--significantly higher than the levels in the control volunteers. CONCLUSION: Plasma concentrations of the soluble form of P-selectin were markedly higher in patients with AMI, suggesting the activation of platelets, or endothelial cells, or both. Thus, quantitative measurements of plasma P-selectin concentrations may help to assess the pathophysiology of inflammatory reactions in patients with AMI.

Adult↗
PubMed1994

[A coagulative type of pulmonary surfactant depletion--a mechanism of damage to the pulmonary surfactant system].

Plasma proteins, in particular fibrinogen and its degradation products leaking into air spaces in various forms of lung injuries, can adversely affect surfactant function. Two types of interaction of pulmonary surfactant with plasma proteins have been described: (1) a reversible type of interaction of surfactant with plasma proteins, and (2) a coagulative type of surfactant inactivation. The physiological significance of the latter mode of surfactant inactivation remains controversial. The purpose of this study was to determine the relative importance of these two modes of surfactant inactivation in an alveolar model. Surfactant-fibrinogen mixtures were prepared by adding fibrinogen at various concentrations to a standard preparation of surfactant-TA (suspended in Tris buffered saline at the final concentration of 1.25 mg/ml). To one of the mixtures were added caCl2 and thrombin, and the resulting fibrin clot was removed from the mixture by passing through polyethylene telephthalate filter. The surface activity of surfactant-TA suspension and the mixtures of surfactant-TA and fibrinogen before and after fibrin formation was examined during adsorption and dynamic compression using a pulsating bubble surfactometer. The concentrations of total phospholipid and surfactant-associated proteins (SP-B and SP-C) were also measured in these samples. Similar studies were performed with natural surfactant and dipalmitoylphosphatidylcholine (DPPC). Retarded adsorption of surfactant-TA and an increased minimum surface tension were observed in fibrinogen concentrations exceeding 2(-5) mg/ml. The inhibitory effect of fibrinogen on surfactant function reversed completely by 10-min after dynamic bubble pulsations. The magnitude of retarded adsorption and a lessening the ability to lower the minimum surface tension during dynamic bubble compression were significantly greater in the surfactant-fibrinogen mixtures after removal of the fibrin clots than in those before fibrin formation in fibrinogen concentrations exceeding 2(-3) mg/ml. More than 90% of both phospholipid and SP -B, C of surfactant-TA was incorporated into the fibrin clot in fibrinogen concentrations of > 2(-3) mg/ml. Similar results were obtained with natural surfactant or DPPC. At a fixed fibrinogen concentration of 2 mg/ml the fibrin clot removal was accompanied by a 90% loss of surfactant-TA in its concentration range of 1.25-40 mg/ml. Scanning electron microscopic examinations showed that numerous particles of surfactant-TA were seen embedded in fibrin network. The results of this study suggest that the coagulative type of pulmonary surfactant depletion may be more important than the reversible type of pulmonary surfactant inactivation by fibrinogen.

Fibrin↗
PubMed1994

Prevention of spontaneous polyarthritis in NZB/KN mice by treatment with a novel thiazole derivative, SM-8849.

NZB/KN mice spontaneously develop polyarthritis, characterized by infiltration of inflammatory cells into the synovium and destructive damage of articular cartilage and bone. This study was performed to elucidate the effects of a novel thiazole derivative (SM-8849; (4-[1-(2-fluoro-4-biphenylyl)-ethyl]-2-methylamino thiazole) in comparison with the cyclooxygenase inhibitor, indomethacin, on disease development and immune disorders in NZB/KN mice. Mice were treated with SM-8894 (50 mg/kg) or indomethacin (2 mg/kg), starting from two months of age, for seven months. Indomethacin had no inhibitory effect on joint lesions in this model. In contrast, SM-8849 was effective in arresting the progression of arthritis, as confirmed by histologic and radiographic studies. Moreover, SM-8849, but not indomethacin, suppressed rheumatoid factor production. In addition, the population of CD5+ B cells in the peritoneal cavity and spleen was reduced with SM-8849 treatment. These findings suggest that NZB/KN mice are of use in the evaluation of intrinsic antiarthritic activity, independently of cyclooxygenase inhibition. Additionally, the therapeutic value of SM-8849 is strongly suggested by its efficacy in this model.

Animals↗
PubMed1994

[Osteoarthritis of the knee joint: a field study].

To clarify the natural history of osteoarthritis of the knee joint, a field study of the knee joint was performed on the inhabitants of Matsudai Town, Niigata Prefecture in 1979 and 1986. The study included the same 979 individuals, involving 820 women and 159 men, aged between 40 and 65 years in 1986 as in 1979. Narrowing of the femoro-tibial joint space was found in 17.7% and 26.1% of the women, and in 5.3% and 12.0% of the men, in 1979 and 1986, respectively. The individuals without osteoarthritic change and those with subchondral sclerosis or osteophytes in the femoro-tibial joint space exhibited less progressive changes in symptoms and radiographic findings. On the other hand, many of those in whom the joint space was more than 50% narrowed compared with the contralateral joint space had persistent pain, suggesting that they were candidates for active treatment. There were about twice as many women as men with symptomatic osteoarthritis of the knee. A comparative study of a group of women with, and a group of women without, radiographic progression in arthritic changes, indicated that the factors correlated with worsening osteoarthritis of the knee included aging, obesity, varus deformity of the knee, severity of inflammation, and flexion contracture of the knee.

Adult↗
PubMed1994

[Anaphylactic shock by ophthalmic wash solution containing chlorhexidine].

A 58 year-old male patient developed anaphylactic shock, possibly due to the use of chlorhexidine as ophthalmic wash solution. He was successfully resuscitated without any sequelae. The patient had increased levels of both histamine and tryptase. The skin test for allergy resulted in strong positive to chlorhexidine. There have been many reports regarding severe adverse reactions associated with use of chlorhexidine. It is necessary to pay attention to anaphylactic shock due to chlorhexidine.

Anaphylaxis↗
PubMed1994

[Mechanism and prevention of postoperative hemolysis in the corrective surgery of subarterial ventricular septal defects].

Intravascular hemolysis following the repair of subarterial ventricular septal defects (VSD) was studied in 34 patients. The VSD was closed through a main pulmonary arteriotomy with a Dacron double-velour patch (Meadox, Oakland, NJ) in 17 cases (Group B) and with a Dacron single-velour patch covered by autologous pericardium facing toward the right ventricular outflow tract (RVOT) in 17 cases (Group A). No significant intergroup difference in age, weight, Qp/Qs, Pp/Ps, and Rp/Rs was found. There were no significant differences in the preoperative values of serum LDH, total bilirubin, and flow velocity at the RVOT (Group A: 1.7 +/- 0.4 m/sec vs Group B 1.8 +/- 1.0 m/sec). The severity of hemolysis was evaluated by serum LDH levels, total bilirubin levels, and hemoglobinuria on the morning of the first operative day. Postoperative LDH levels were significantly lower in the Group A (812 +/- 205 IU/L) than in the Group B (1098 +/- 427 IU/L) (p < 0.05). Hemoglobinuria developed in 2 patients in Group B (12%) and none in Group A. These data suggest that the pericardium apparently protects against postoperative hemolysis. The intensity of the turbulence at the RVOT was graded as follows using color-doppler echocardiography (0: none; Grade 1: turbulence was detected near the patch only; Grade 2: turbulence was detected halfway to the RVOT; Grade 3: turbulence extended to the anterior wall of the RVOT). The relationship between the presence of hemolysis and the degree of turbulence was examined. Turbulence at the RVOT appeared in 73% of those in Group A and in 82% of those in Group B.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

[Acute arterial occlusion of the lower extremities].

The clinical course of 40 patients with acute arterial occlusions of a lower extremity was reviewed with special reference to the etiology. Patients were classified into three groups: arterial embolism (10 patients), acute atherosclerotic thrombosis (AAT) (13 patients), and miscellaneous (17 patients). Circulation was restored in 83% of cases; embolism, 100%; AAT, 55%; and miscellaneous 88%. Five patients (13%) died, including 2 of MNMS (Myo-nephropathic-metabolic syndrome). MNMS developed in 1 patient in the embolism, 2 patients in the AAT, and 5 patients in the miscellaneous group. The five patients with MNMS in the embolism and miscellaneous groups were treated between 6 to 12 hours following the onset of symptoms, while both patients in the AAT group were not treated until 24 to 72 hours following occlusion. Revascularization was successful in the AAT group even when the ischemia lasted for 6 to 8 hours. However, patients in the embolism and miscellaneous Groups, who lacked effective collateral circulation, were at greater risk for developing MNMS when ischemia last for more than 6 hours.

Acute Disease↗
PubMed1994

Role of serum interleukin-8 and intercellular adhesion molecule-1 in the severity of alcoholic hepatitis.

Among patients with alcoholic hepatitis, three groups were distinguished by histological findings and clinico-pathological features. The aim of this study was to clarify the role of soluble intercellular adhesion molecule-1 (sICAM-1) and interleukin-8 (IL-8) in the development of severe alcoholic hepatitis. The levels of sICAM-1 and IL-8 were well correlated with the severity of liver injuries. The concentrations of serum IL-8 were significantly correlated with the number of polymorphonuclear leukocytes infiltrating the liver. Serial determination of these two markers revealed that IL-8 may be complementary in assessing the severity and prognosis of alcoholic hepatitis.

Adult↗
PubMed1993

Extensive apoptosis occurring in the thymus during accelerated rejection of cardiac allografts in presensitized rats.

Cardiac allografts of (Lewis x Brown Norway) F1 rats are rejected by Lewis recipients at 7.5 days after engrafting. When recipients are presensitized with Brown Norway skin grafts at 7 days before engrafting, the cardiac grafts are rejected between 24 and 36 h (accelerated rejection, ACR). We previously demonstrated that the number of thymocytes in recipients showing ACR is decreased to approximately one eighth at 24 h after engrafting, and the thymocytes remaining in the thymus are phenotypically and functionally more mature. In the present study, flow cytometric analysis of the thymocytes in the sensitized recipient at 24 h after engraftment demonstrated that the frequency of single positive cells (CD4+CD8- and CD4-CD8+) was increased and that of double positive cells (CD4+CD8+) was decreased, indicating that immature thymocytes preferentially disappeared during the ACR episode. Thymocytes of the recipients undergoing ACR suffered from extensive apoptosis, characterized by chromatin condensation in the nuclei, cell shrinkage, nuclear collapse, and DNA fragmentation. Serum levels of corticosterone were elevated but were within a similar range among the transplant recipients destined for acute rejection, those undergoing ACR, and isografted controls, suggesting the participation of mediator(s) other than glucocorticoid in the induction of extensive apoptosis in the transplant recipients with ACR. We propose that thymocyte apoptosis is accelerated during the allograft rejection episode.

Animals↗
PubMed1993

Cyclic flow variations in a conscious dog model of coronary artery stenosis and endothelial injury correlate with acute ischemic heart disease syndromes in humans.

OBJECTIVES: The purpose of this study was to test the hypothesis that episodes of cyclic flow variations (CFVs) in conscious dogs with coronary stenoses and endothelial injury correlate with acute ischemic heart disease syndromes in humans. BACKGROUND: Although the canine model with CFVs has proved to be a useful model of coronary thrombosis, whether CFVs progress to these syndromes has not been clearly described. METHODS: Cyclic flow variations were produced by an external constrictor placed at the site of the left anterior descending coronary artery with injured endothelium. Blood flow in this artery and 24-h Holter electrocardiogram (ECG) were recorded during the 1st 5 postoperative days. RESULTS: Of 41 dogs that underwent the initial operative procedure successfully, 29 developed an episode of CFVs. In five dogs in which CFVs persisted throughout the monitoring period, the left anterior descending coronary artery flow decreased until day 3 and thereafter increased through day 5. Transient coronary occlusion during CFVs induced ST segment changes that returned to baseline after reflow. In 12 dogs, CFVs progressed to persistent coronary occlusion, and histologic examination revealed thrombus formation at the stenotic site and evidence of myocardial infarction. Four of these 12 dogs died suddenly of ventricular arrhythmias during persistent coronary occlusion; another 5 dogs died of reperfusion arrhythmias during CFVs with no evidence of myocardial infarction. CONCLUSIONS: Conscious dogs with CFVs closely correlated with clinical acute ischemic heart disease syndromes, suggesting them to be a useful model for investigating the complex mechanisms of cellular interactions in the pathogenesis of these syndromes.

Animals↗