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Biomedical subjects

M Mitani

Publications and source records attributed to M Mitani.

At least 19 recordsLinked to original sources
PubMed1992

[MR angiography of the lung using 3-dimensional imaging method].

Three-Dimensional MR angiography (3D-MRA) of the lung was performed in 5 healthy volunteers and 14 patients with primary pulmonary cancer in the hilum, and compared with 2D-MRA. As 3D-MRA could be obtained with single breath holding after intravenous bolus injection of Gd-DTPA, pulmonary vessels of the hilum and peripheral zone were demonstrated more definitely than those of 2D-MRA. In all patients except one case, the relation between the tumor and pulmonary vessels was visualized more clearly by 3D-MRA than 2D-MRA. This technique is considered a non-invasive and effective method for evaluation of pulmonary vessels in the patient with hilar tumor.

Humans↗
PubMed1992

[Hepatic arteriography under temporary hepatic venous occlusion].

Hepatic arteriography with and without temporary segmental hepatic vein occlusion was performed in 10 patients, five of whom had chronic liver injury. Hepatic arteriograms obtained during hepatic venous obstruction demonstrated significantly more peripheral and definite arterial branches in the occluded area and fewer peripheral branches in the non-occluded segment. A prolonged, dense hepatogram (sinusoidogram) showing hepatofugal opacification of the portal vein was obtained in the occluded area. Only one case with a large veno-venous anastomosis did not show these findings. Hepatic arteriograms in two cases with hepatocellular carcinoma provided clear visualization of peripheral portal branches that could act as efferent tumor vessels during regional temporary hepatic vein occlusion. Temporary hepatic venous occlusion may cause a sudden increase of hepatic arterial flow in the occluded area and transsinusoidal arterioportal communication there. This method can be useful for the diagnosis and arterial infusion or embolization therapy of hepatic diseases.

Adult↗
PubMed1992

[Clinical experience of continuous retrograde cerebral perfusion for assisted circulation during the surgical treatment of acute dissection of aorta: Stanford A type].

Surgical treatment of the dissection involving the ascending aorta or aortic arch represents one of the most complicated technical challenges. Recently continuous retrograde cerebral perfusion (CRCP) is sometimes applied in order to avoid cerebral complications. We compared two surgical groups, one of which was performed graft-replacement of ascending aorta using CRCP and another was utilized normograde cerebral circulation, about the technique of operation, total extracorporeal circulation (ECC) time, aortic clamp time, separate ECC time, total bleeding volume, and urination during operation. In the group using CRCP, separate ECC time was 53 min (mean), and intraoperative bleeding volume was only 1,170 ml. Good urination was obtained during operation. Postoperative courses were uneventful, and consciousness was smoothly and soon recovered. The new method of separate ECC has some advantages over the previously described methods, particularly for avoidance of cerebral complications. As it is not necessary to require dissecting, taping, and clamping of cephalic branches, operative procedure will be very simplified, easier and safer, leading to intraoperative bleeding is a fewer. It is our belief that this method should be widely applied in the operation of graft-replacement of ascending aorta or aortic arch in the near future.

Aged↗
PubMed1991

Specific association of retroviral envelope protein, p15E, with human cell surfaces.

Experiments were carried out to analyze the binding sites on human cells for highly purified retroviral protein p15E isolated from Feline Leukemia Virus, Rickard Strain. Binding of 125I-labeled p15E was tested with surfaces of human peripheral blood lymphocytes and 3 cell lines, Raji, MOLT-4, and U-937. 125I-labeled p15E showed specific binding to human peripheral blood lymphocytes. In addition, all of the cell lines tested showed binding of 125I-labeled p15E. Using U-937 cells, we characterized the interaction between p15E and the surface of these cells, and showed that the binding was specific by the following 3 different sets of evidence: (i) in equilibrium binding experiments, 18,000 binding sites with a dissociation constant of 2 x 10(-9) M were present on U-937 cells; (ii) trypsin or N-glycanase treatment decreased the binding sites of 125I-labeled p15E; and (iii) by affinity chromatography using p15E or BSA Sepharose columns, the isolated membranes of 125I-labeled U-937 cells previously treated with Triton X-100 showed a significantly higher binding to the p15E column than to the BSA column.

Amidohydrolases↗
PubMed1991

Application of Doppler color flow imaging to determine valve area in mitral stenosis.

This study was undertaken to examine whether Doppler color flow imaging could accurately estimate the valve area in mitral stenosis. Doppler color flow assessments were performed in both an in vitro model and in 30 patients with mitral stenosis undergoing cardiac catheterization. In the experimental Doppler study using a circuit model, color jet width correlated well with actual orifice diameter (r = 0.99). In the clinical Doppler study, the mitral valve orifice was assumed to be elliptic and the mitral valve area was calculated from the following equation: (pi/4) (a x b), where a = color jet width at the mitral valve orifice in the apical long-axis view (short diameter) and b = the width in the 90 degrees rotated view (long diameter). Mitral valve area was also determined by two-dimensional echocardiography and the pressure half-time method, and the results for all three noninvasive methods were compared with those obtained at cardiac catheterization. By Doppler color flow imaging, mitral valve area could be determined in all patients and there was a significant correlation between the Doppler jet and catheterization estimates of mitral valve area (r = 0.93). Valve area determined by two-dimensional echocardiography correlated well with catheterization measurements in 26 patients (r = 0.84). However, the area could not be determined in 4 (13%) of the 30 patients because of technical problems. Although there was a fair correlation between the valve area determined by the pressure half-time method and catheterization (r = 0.79), this method tended to overestimate valve area in patients with aortic regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
PubMed1991

Intracardiac mobile thrombus and D-dimer fragment of fibrin in patients with mitral stenosis.

OBJECTIVE: To investigate the relation between intracardiac thrombus and blood coagulability in patients with mitral stenosis. DESIGN: Prospective study. Cross sectional echocardiography and plasma concentrations of the D-dimer fragment of fibrin were used concurrently to detect intracardiac thrombus in patients with mitral stenosis. SETTING: Department of Medicine, National Cardiovascular Centre, Osaka, Japan. PATIENTS: 63 patients with mitral stenosis. None of them had been receiving any anticoagulants or antiplatelet agents. MAIN OUTCOME MEASURES: Plasma concentrations of D-dimer in patients with a mobile intracardiac thrombus, those in patients with a non-mobile intracardiac thrombus, and those in patients without an intracardiac thrombus. RESULTS: A mobile intracardiac thrombus was found in 10 patients and a non-mobile thrombus in eight. The remaining 45 patients had no intracardiac thrombi. Plasma concentrations of D-dimer in the 10 patients with a mobile thrombus were all greater than 300 ng/ml (mean 983.3, 95% confidence interval 498.9 to 1467.7 ng/ml) and they were significantly higher than those in the patients with a non-mobile thrombus (226.2, 33.6 to 418.8 ng/ml) and the patients without an intracardiac thrombus (147.2, 110.4 to 184 ng/ml). CONCLUSIONS: A high plasma concentration of D-dimer seemed to reflect a hypercoagulable intracardiac state and may be a helpful indicator of the possible presence of mobile intracardiac thrombus in patients with mitral stenosis.

Antifibrinolytic Agents↗
PubMed1991

Detection of human factor B biosynthesis in culture supernatants and cell lysates by ELISA.

We report here on the development of a simple, sensitive, convenient, and quantitative enzyme-linked immunosorbent assay for human factor B, a protein of the alternative complement pathway, by the sandwich method using goat anti-human factor B antibody. The assay described herein is reproducible and highly specific for human factor B. The assay was used to determine biosynthesis (cell lysates or extracts) and secretion (supernatants) of human factor B using human monocyte cell line U937. Phorbol myristate acetate strongly enhanced (10- to 20-fold) biosynthesis of factor B by U937. The combination of a sensitive enzyme-linked immunosorbent assay and phorbol myristate acetate enabled us to use a microculture system.

Antimetabolites↗
PubMed1991

[A case of liver cirrhosis associated with chronic subdural hematoma and hepatic encephalopathy].

A 58-year-old male liver cirrhosis patient, who had a history of recurrent hepatic encephalopathy, was admitted to our hospital because of clouding of consciousness. He had an episode of recent head trauma. On admission, he was drowsy and exhibited flapping tremor, fetor hepaticus and ascites. Laboratory data showed an increase in blood ammonia level, and a decrease in peripheral thrombocytes, serum albumin and prothrombin value. A ratio of branched-chain to aromatic amino acids was reduced. Antibody against hepatitis C virus was positive. His electroencephalogram showed bilaterally large synchronous slow waves. He was treated with intravenous branched-chain amino acids, and recovered. Cranial computed tomography on day 9 demonstrated a crescent shaped area of low density in the right frontotempoparietal subdural region. He was diagnosed as chronic subdural hematoma, which was treated surgically. It has been suggested that chronic subdural hematomas develop as a complication of hemostatic deficiency due to liver cirrhosis.

Chronic Disease↗
PubMed1991

The suppressive effect of a synthetic retroviral peptide on the human IFN gamma production is abrogated by the combined stimulation with IL-1 and IL-2.

Certain retroviral envelope proteins and peptides have been shown to be highly immunosuppressive. Recently, we have demonstrated that a synthetic 17 amino acid peptide (CKS-17*) homologous to a highly conserved region in the transmembrane portion of the envelope of several human or animal retroviruses suppresses the production of human interferon-gamma (IFN gamma) by human peripheral blood leukocytes (PBL). In the present investigation, we studied the role of exogenous IL-1 or IL-2, and IL-1 plus IL-2 on the suppressive action of CKS-17* in the production of IFN gamma. The results showed that preculture of PBL with CKS-17* reduced the production of IFN gamma in a dose-dependent manner. The addition of IL-1 or IL-2 reduced, in part, this suppression of IFN gamma production. Full abrogation of the inhibition attributable to CKS-17, however, occurred only when PBL precultured with CKS-17* were recultured with staphylococcus enterotoxin A (SEA) together with exogenous IL-1 plus IL-2. These results show that the inhibition of IFN-gamma production by CKS-17* is reversible. The findings indicate that cytokines can modulate certain of the immunosuppressive actions attributable to retroviruses or their components and suggest that some cytokines influence immunosuppressive consequences of retroviral infection.

Cells, Cultured↗
PubMed1990

Inhibition of murine cytotoxic T lymphocyte activity by a synthetic retroviral peptide and abrogation of this activity by IL.

A synthetic 17 amino acid peptide (CKS-17) homologous to a highly conserved region of human and animal retroviral transmembrane proteins was investigated for its influence on the generation of murine alloantigen-specific CTL activity in vitro. CKS-17 coupled to a carrier protein, BSA or human serum albumin, inhibited the generation of anti-allo CTL in a dose-dependent manner. Controls consisting of BSA and human serum albumin, which had undergone the coupling procedure or neurotensin, an unrelated peptide, coupled to BSA in an identical manner as CKS-17 showed no such inhibitory action. The suppression was not restricted to the Ag specificity of the CTL activity. CKS-17 exerted inhibitory effects on the early afferent phase of CTL induction. Kinetic studies showed that the suppressive activity occurred when CKS-17 was introduced to the immunologically stimulating culture concomitant with or up to 48 h after initiation of culture. Analysis of the frequency of CTL precursor cells using limiting-dilution assays revealed that CKS-17 did act to reduce the number of precursor cells. Abrogation of the inhibition of CTL activity was observed when IL-2 was introduced to the culture together with the stimulator cells. Other lymphokines, such as IL-4, exerted a similar influence to counteract this suppression.

Animals↗
PubMed1990

Intraoperative localization of a cervicomedullary glioma from the killed end potential: illustrative case.

We recorded the intraoperative somatosensory evoked potentials directly from the upper cervical cord and medulla in a patient with an intrinsic tumor at the region of the cervicomedullary junction. The killed end potential, a large positive potential, was obtained at the caudal end of the tumor. This type of potential occurs when an impulse approaches but never passes beyond the recording electrode. Myelotomy guided by the killed end potential enabled appropriate spinal and medullary dissection and led to early encounter with the cervicomedullary tumor.

Adult↗
PubMed1989

Characterization of the critical state in protein folding. Effects of guanidine hydrochloride and specific Ca2+ binding on the folding kinetics of alpha-lactalbumin.

The reversible unfolding and refolding kinetics of alpha-lactalbumin induced by concentration jump of guanidine hydrochloride were measured at pH 7.0 and 25 degrees C using tryptophan absorption at 292 nm, with varying concentrations of the denaturant and free Ca2+. The refolding reaction of alpha-lactalbumin from the fully unfolded (D) state occurs through the two stages: (1) instantaneous formation of a compact intermediate (the A state) that has a native-like secondary structure; (2) tight packing of the preformed secondary structure segments to lead finally to the native structure, this stage being the rate-determining step of the reaction and associated with acquisition of the specific structure necessary for strong Ca2+ binding. Under strongly native conditions, the observed kinetics of refolding is also complicated by the presence of a slow-folding species (10%) in the unfolded state. Considering these facts, the microscopic rate constants in folding and unfolding directions have been evaluated from the observed kinetics and from the equilibrium constants of the transitions among the native (N), A and D states. Close linear relationships have been found in the plots of the activation free energies, obtained from the microscopic rate constants, against the denaturant concentration. They are similar to the linear relationship between the free energy of unfolding and the denaturant concentration. It was demonstrated that the slope of the plots should be approximately proportional to a change in accessible surface area of the protein during the respective activation process, and that only a third of the difference in accessible surface area between A and N is buried in the critical activated state of folding. However, the selective effect of Ca2+ binding on the folding rate constant has been observed also, demonstrating that the specific Ca2+-binding substructure in the N state is already organized in the activated state. Thus, only a part of the protein molecule involving the Ca2+-binding region is organized in the activated state, with the other part of the molecule being left less organized, suggesting that the second stage of folding may be a sequential growing process of organized assemblage of the performed secondary structure segments.

Animals↗
PubMed1989

Anti-tumor cytostatic mechanism and delayed-type hypersensitivity against a syngeneic murine tumor. Comparison between neonatally thymectomized mice and congenitally athymic nude mice.

We studied the anti-tumor mechanism against a syngeneic tumor using a BALB/c-MA tumor system by cytolysis and cytostasis assays in vitro comparing mice neonatally thymectomized at 1 day or 7 days after birth (NTx-1, NTx-7), sham-operated (sham) mice, and congenitally athymic nude BALB/c mice. NTx-1 mice showed more rapid tumor growth and a slightly lower degree of strong cytostatic activity in peritoneal exudate cells (PEC) than NTx-7 or sham mice. Nude mice showed more rapid MA growth than NTx-1 mice and no cytostatic activity in PEC. After immunization with mitomycin C-treated MA (MMC-MA), NTx-1 mice acquired an immunoprophylactic capacity against MA and showed cytostatic activity and delayed footpad reaction (DFR) to MA, however, nude mice showed no acquisition of such an immunity, or cytostatic activity, or DFR to MA. These differences between NTx-1 and nude mice could be well-explained by less capacity of nude mice to produce a macrophage-activating factor, which activates macrophages to exert cytostasis and DFR. However, NTx-1 mice could not reject MA by immunization with MMC-MA in CFA (MMC-MA/CFA), although such immunized sham mice could eliminate MA completely. Both PEC and spleen cells from Sham mice immunized with MMC-MA/CFA showed cytostatic activity, whereas NTx-1 mice showed cytostatic activity of the same level in PEC and less in spleen cells compared to Sham mice. Cytolytic activity was never detected throughout this study in a BALB/c-MA system. These data suggest that cytostasis plays an important role in antitumor immunity against a syngeneic MA tumor and that two types of cytostasis is included from the standpoint of thymus-dependency of ontogenic development, relatively low and high.

Animals↗
PubMed1989

Role of cytostasis in antitumor immunity against syngeneic X5563 plasmocytoma: comparative study of cytostasis and cytolysis using variant tumors and neonatally thymectomized mice.

The mechanism of antitumor immunity against syngeneic X5563 plasmocytoma was investigated with cytostasis and cytolysis assays by changing the host-tumor interrelationship using neonatally thymectomized (NTx) mice and spontaneous variant tumors. Immunization with mitomycin C-treated X5563 cells (MCC-X5563) in complete Freund's adjuvant (CFA) induced an effective anti-X5563 immunoprophylaxis in vivo. Such immunized mice and X5563 tumor-bearing mice showed cytostatic, but not cytolytic, activity in their peritoneal exudate cells (PEC) in vitro. Both cytostatic and cytolytic activities were induced in PEC of regressor (R1 and R2) variant tumor-bearing mice. But NTx mice, which could exert cytostatic activity and no cytolytic activity, could reject about one-half of R1 variant tumors. Immunizations using a progressor P1 variant tumor, obtained from R1 tumor after nearly complete rejection, did not give a prophylactic effect in vivo, nor did they induce in vitro cytolytic activity although a low degree of cytostatic activity was detected. These results suggest that cytostasis is the common and basic effector mechanism of antitumor resistance against syngeneic original or variant X5563 tumors, and that the collaboration of cytolysis and cytostasis exerts strong resistance against regressor variants.

Animals↗
PubMed1989

Surgical indications in children with cerebral palsy.

We have presented our approach to the surgical consideration for the upper extremities of a child with cerebral palsy. This is basically a coordinated approach involving many team members, and is the only way to achieve predictable postoperative results.

Cerebral Palsy↗
PubMed1988

Human IFN-gamma production is inhibited by a synthetic peptide homologous to retroviral envelope protein.

A synthetic 17 amino acid peptide (CKS-17) homologous to a highly conserved region of human and animal retroviral transmembrane proteins was investigated for its influence on the in vitro production of IFN-gamma from human peripheral mononuclear cells. The results showed that CKS-17 coupled to a carrier protein, BSA, inhibited production of IFN-gamma in a dose-dependent manner. Controls, consisting of BSA, which had undergone the coupling procedure or neurotensin coupled to BSA in an identical manner as CKS-17, showed no such inhibition. Reduction in IFN-gamma production could not be attributed to decreased viability of cells, delay of IFN-gamma production or to involvement of suppressor cells. Moreover, inhibition of IFN-gamma production was not related to the inhibition of DNA synthesis. The inhibition appeared to be a direct effect of CKS-17 on IFN-gamma-producing cells. Kinetic studies revealed that this suppression occurred when CKS-17 was introduced to the culture concurrent with or within 48 h after introduction of IFN inducers. Preincubation experiments showed that the presence of CKS-17 in the culture medium was not necessary to exert its inhibitory effect. These results suggest that a portion of retroviral envelope proteins possess important immunomodulatory actions.

Amino Acid Sequence↗
PubMed1988

In vitro production of feline IgG: quantification by an enzyme-linked immunosorbent assay (ELISA).

We report here on the development of a sensitive and convenient enzyme-linked immunosorbent assay (ELISA) for feline IgG by using commercially available reagents and optimizing their concentrations. The reagents employed include goat anti-cat IgG antibody and alkaline phosphatase-conjugated goat anti-cat IgG antibody. The assay described is sensitive, reproducible, and highly specific for feline IgG. The assay was applied for the measurement of feline IgG synthesized and secreted in vitro by peripheral blood mononuclear cells cultured with or without a polyclonal B-cell activator. The amounts of secreted IgG in the supernatants measured by an ELISA correlated well with the numbers of IgG-secreting cells which were induced upon stimulation with pokeweed mitogen and determined by a reverse hemolytic plaque assay.

Animals↗