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Biomedical subjects

K Masuda

Publications and source records attributed to K Masuda.

At least 487 records · Page 27Linked to original sources
PubMed1991

Differentiation of central lung tumor from postobstructive lobar collapse by rapid sequence computed tomography.

When central lung tumor is associated with lobar collapse, discrimination of tumor from atelectasis is important for determining operability or for field planning should radiation therapy be utilized. Because tumor and collapsed lung have similar attenuation values, they cannot always be distinguished with usual contrast-enhanced CT. The article describes separation of tumor from collapsed lung by means of RSCT with bolus injection of nonionic contrast medium. With this technique collapsed lung is appreciably enhanced, but tumor enhancement is slow and minimal. The difference is most marked from 40 seconds to 2 minutes after scanning begins. This phenomenon is probably related to the marked increase in blood flow per unit area of collapsed lung due to crowding of relatively large pulmonary arteries compared to tumor blood supply through small bronchial arteries. Tumor can also be delineated from atelectasis by differences in internal structure with this technique.

Aged↗
PubMed1991

Striatal blood flow, glucose metabolism and 18F-dopa uptake: difference in Parkinson's disease and atypical parkinsonism.

Striatal blood flow, glucose metabolism and 18F-Dopa uptake were studied with positron emission tomography (PET) in eight non-demented patients with idiopathic Parkinson's disease and eight with atypical Parkinsonism. Patients with atypical Parkinsonism had no specific cause for the Parkinsonian symptoms and were clinically different from Parkinson's disease with lack of resting tremor and a poor response to dopaminergic drugs. Decreased 18F-Dopa uptake in the putamen was observed in patients with Parkinson's disease and atypical Parkinsonism compared with normal controls. 18F-Dopa uptake in the head of the caudate was also significantly reduced in both conditions but relatively less in Parkinson's disease. Decreased blood flow and glucose metabolism in the striatum associated with a global cerebral decrease were also observed in patients with atypical Parkinsonism compared with controls, while they were preserved in patients with Parkinson's disease, indicating affected neurons not only in the striatum but also in the cerebrum in patients with atypical Parkinsonism compared with patients with Parkinson's disease. The differences in the caudate 18F-Dopa uptake, and blood flow and glucose metabolism in the cerebrum including the striatum between Parkinson's disease and atypical Parkinsonism assessed by PET may be due to the differences in the pathophysiological mechanism between Parkinson's disease and atypical Parkinsonism.

Adolescent↗
PubMed1991

Polymorphonuclear leukocyte heterogeneity of Fc receptor expression and membrane potential in human neonates.

In order to clarify the relationship among polymorphonuclear neutrophil (PMN)-related phenomena, i.e. the Fc receptor expression, the ionic condition of the plasma membrane and chemotactic response, we determined percentage of EA rosette-forming PMN (RFN), membrane potential and PMN chemotaxis in 15 neonates. RFN was assessed by the whole blood method as well as the purified PMN. Membrane potential was examined using the lipophilic fluorescent cyanine dye, 3,3'-dipentyloxacarbocyanine [di-O-C5(3)] and flow cytometry. Both parameters were measured with resting PMN. Numbers of RFN by the two methods have a significant correlation (p less than 0.01, r = 0.881, n = 15). Number of RFN by the whole blood method had a significant correlation with membrane potential (p less than 0.01, r = 0.703, n = 14). Furthermore, number of RFN and membrane potential were significantly correlated with PMN chemotaxis, respectively (p less than 0.01, r = 0.781, n = 14; p less than 0.01, r = 0.695, n = 10). When we examined the effect of beta-adrenergic agents and prostaglandin E1 on number of RFN, membrane potential and PMN chemotaxis, and attempted to confirm the interrelation among these parameters, we observed that PMN chemotaxis was markedly depressed so were both number of RFN and membrane potential. These findings indicate that impaired PMN chemotaxis may in part be related to a decrease in both rosette formation capacity of PMN and membrane potential.

Alprostadil↗
PubMed1991

Purification and characterization of aseanostatins: actinomycete-derived fatty acid inhibitors to myeloperoxidase release from human polymorphonuclear leukocytes.

We found inhibitors, designated aseanostatins P1 and P5, against myeloperoxidase (MPO) release from human polymorphonuclear leukocytes (PMN). Aseanostatins were extracted from an actinomycete isolated in Thailand and purified by a series of column chromatography of charcoal and silica gel, and HPLC. Physico-chemical characterization by gas liquid chromatography and GC-MS indicated that aseanostatins were fatty acids. The active forms of aseanostatins were recovered by hydrolyzing their methyl esters after HPLC. Two components P1 and P5 with the IC50 of 0.96 and 0.54 microgram/ml to the MPO release were obtained as pure forms, indicating aseanostatin P5 was higher activity than aseanostatin P1. The component P1 was identical with 12-methyltridecanoic acid and P5 was indistinguishable to 12-methyltetradecanoic acid (ante-i-15:0). Aseanostatin P5 (1 microgram/ml) did not inhibit beta-glucuronidase release, but O2- production a little. It has no effect on chemotaxis of PMN to fMet-Leu-Phe (10(-8)M), PMN adhesion or phosphorylation of a 64-kD protein in the PMN cell-lysate system.

Actinomycetales↗
PubMed1991

Pyrrolomycin group antibiotics inhibit substance P-induced release of myeloperoxidase from human polymorphonuclear leukocytes.

In order to search for microbial modulators of the activity of neuropeptide, we established a screen based on substance P (SP)-induced myeloperoxidase (MPO) release from human polymorphonuclear leukocytes (PMN). SP induced MPO release in a dose-dependent manner at concentrations ranging from 1 approximately 10 x 10(-4) M. In comparison at 1 x 10(-4) M, induction was also observed with SP derivatives but not with other neuropeptides such as neurokinin and enkephalin. Based on this, we searched for microbial inhibitors against SP-induced MPO release. An actinomycete metabolite designated HS3, which turned out to be identical with dioxapyrrolomycin or A1-R2081, and structurally related pyrrolomycins were found to inhibit SP-induced MPO release. In addition, these compounds inhibited the f-Met-Leu-Phe (FMLP)-induced MPO release from PMN. Pyrrolomycin derivatives with an N-methylated pyrrole ring showed, however, a selective inhibition of the SP-induced MPO release. This was in contrast to results with aseanostatin P5 which selectively inhibited FMLP-induced MPO release.

Actinomycetales↗
PubMed1991

Interleukin 1 and tumor necrosis factor-alpha synergistically increase the production of interleukin 6 in human synovial fibroblast.

We have previously reported that synovial cells could participate in B cell differentiation processes in rheumatoid arthritis (RA) by producing interleukin-6 (IL-6) spontaneously or in response to interleukin-1 (IL-1) stimulation. In this paper, we examined the effects of tumor necrosis factor-alpha (TNF-alpha) on IL-6 production by human synovial fibroblasts. TNF-alpha, as well as IL-1, is a putative relevant molecule in the inflammatory process and in articular destruction in RA. Both IL-1 and TNF-alpha induced IL-6 production by synovial fibroblasts in a dose dependent manner. When synovial fibroblasts were stimulated by IL-1 and TNF-alpha in combination, IL-6 production increased synergistically after 48 hr of a 72 hr culture period. Kinetic studies revealed that the presence of both cytokines at the early phase of stimulation was required for the synergistic effect. These results suggest that TNF-alpha could be involved in a cytokine network in the affected joints of RA and could contribute synergistically with IL-1 to the IL-6 production by synovial fibroblasts in vivo.

Arthritis, Rheumatoid↗
PubMed1991

Ultrasonographic anatomy of veins draining the left lobe of the liver. Feasibility of live related transplantation.

The anatomic variations of the left hepatic vein (LHV) in 182 patients with normal liver functions were analyzed using ultrasonography in order to clarify the feasibility of live related hepatic transplantation (LRHT). LHV was demonstrated in 151 patients (83%). Based on the location of the confluence of the middle hepatic vein (MHV) and LHV and the ramifications of the left medial vein (LMV) and the left superior vein (LSV), the livers were classified into 3 types: a) intrahepatic confluence (42/151 livers, 27.8%); b) extrahepatic confluence (69/151 livers, 45.7%); c) separate insertion (40/151 livers, 26.5%); and 23 subtypes. The length of the common trunk and the intrahepatic common trunk of MHV and LHV and the distance from LMV or LSV to the confluence of MHV and LHV were measured. Overall, the control of LHV in situ for LRHT appeared easy in 34/151 patients (22.5%), while in 44/151 patients (29.1%), the length of free LHV and the common trunk was less than optimal for procurement of a left hepatic lobe graft with complete venous outflow and sufficient extraparenchymal length of LHV.

Adult↗
PubMed1991

Effects of topical application of UF-021, a novel prostaglandin derivative, on aqueous humor dynamics in normal human eyes.

The mechanism underlying the intraocular pressure (IOP) lowering effect of a prostaglandin-related compound, isopropyl 20-ethyl-9 alpha,11 alpha-dihydroxy-15-keto-cis-delta 5-prostanoate (UF-021), and its possible adverse effects in long-term use were studied in normal human eyes. A single instillation of 0.12% UF-021 significantly lowered IOP without affecting aqueous flow rate, tonographic C value or episcleral venous pressure. Protein concentration in the anterior chamber and corneal endothelial permeability to fluorescein remained unaffected. It was suggested that UF-021 lowers IOP mainly by increasing uveoscleral outflow. Twice daily application of 0.12% UF-021 for 4 weeks caused no significant changes in aqueous protein concentration, aqueous flow rate or corneal endothelial permeability. Neither single nor long-term use of topical UF-021 induced irritative responses in the outer segment of the eye. The present study suggests that UF-021 has potential as a safe and effective ocular hypotensive drug with a mechanism of action different from other drugs currently available for the treatment of glaucoma.

Administration, Topical↗
PubMed1991

[The physiological function of human endometrium].

The cyclic change of human endometrial cells are controlled by the interaction between hypothalamus, pituitary gland and ovaries, thus making the endometrium proliferate, differentiate, exfoliate and then reproduce. The menstrual cycle is divided into three phases which are called follicle, ovulatory and luteal phase by the morphological change of the ovarium. The endometrial cycle is also classified to proliferative, secretory and menstrual phase. Estradiol (E2) stimulates the proliferation of endometrial cells by the indirect positive mechanism activated by the binding of E2 to E2 receptor. Growth factors (IGF- I, EGF, TGF- alpha etc.) induced by the transcription of the gene promote the proliferation of endometrial cells. Progesterone (P) has antagonistic effects on E2 actions and transform proliferative phase to secretory phase in endometrium. It is suggested that the possible mechanism of carcinogenesis of normal endometrium is the progression of endometrial hyperplasia due to the prolonged and unphysiological exposure to E2. The additional role of oncogenes (fos, fms, myc, myb, erb-B, neu) and growth factors on the mechanism of carcinogenesis of hyperplasia to cancer is very interested.

Cell Differentiation↗
PubMed1991

Measurement of blood flow velocity in retinal vessels utilizing laser speckle phenomenon.

The laser speckle phenomenon was applied to the measurement of the blood flow velocity in glass capillary tubes and human retinal vessels. The instrument consists of a fundus camera, a He-Ne laser, a photomultiplier, a photon-counting unit, a digital correlator, and a microcomputer system. The scattered laser beam from the retina was detected by the photomultiplier and these signals were processed by the photon-counting unit. The digital correlator and the microcomputer calculated the autocorrelation function of these processed signals. The power of the laser beam was 18 mW/cm2, which was sufficiently below the minimum level considered hazardous to the retina. This technique did not require fine optical alignment and the measurement could be done in 1.05 seconds. A linear relationship between the blood flow velocities in glass capillary tubes and the reciprocal of the correlation time was proved, and the pulsatile flow of a human retinal artery was demonstrated. The reproducibility of the method was 12.4 +/- 6.5% in arteries (Mean +/- SD, n = 4) and 12.4 +/- 5.1% in veins (Mean +/- SD, n = 16). The mean blood flow rate in retinal vessels obtained in this experiment agreed with the values of previous studies. This technique utilizing the laser speckle phenomenon is useful in clinical application to measure the retinal blood flow velocity.

Adult↗
PubMed1991

Transcatheter embolization of testicular vein for varicocele testis.

Percutaneous transcatheter embolization of the testicular vein was performed on 28 patients with angiographically proven varicocele testis. In 2 patients bilateral and in 26 only the left vein was embolized using 3-, 5-, or 8-mm stainless steel coils. All patients had clinically palpable varicoceles and male infertility. The grade of varicoceles improved after embolization in 23 of 28 cases (82%). Effective sperm count increased significantly from 34.5 +/- 44.6 to 65.1 +/- 71.0 following embolization. However, pregnancy was achieved only in one of 28 cases. Technically, the basilic vein approach was felt to be superior to the femoral vein or jugular vein approach for this procedure.

Adult↗
PubMed1991

Assessment of response to cancer therapy using fluorine-18-fluorodeoxyglucose and positron emission tomography.

In order to evaluate the usefulness of 18F-FDG PET in the assessment of therapeutic effects, FDG-PET studies were performed both before and after therapy in 26 patients with miscellaneous malignant tumors. The change in FDG uptake by therapy was compared with the change in tumor size and prognosis. All 26 lesions had a high FDG uptake before therapy. Five of seven lesions which had a relatively low FDG uptake before therapy showed no change or increase in tumor size by therapy. The decreased FDG uptake after therapy was more prominent in the partial response group than in the no change group. FDG uptake before therapy in the non-relapse group was higher than that in the relapse group. However, a decreased FDG uptake did not necessarily indicate a good prognosis. One patient with no change in tumor size and a decreased FDG uptake had no recurrence. This suggests that FDG-PET has a complementary role in the assessment of therapeutic effects.

Adult↗
PubMed1991

[Pure red cell aplasia and pseudothrombocytopenia associated with hepatitis A].

We report a rare case who developed pure red cell aplasia (PRCA) and pseudothrombocytopenia associated with hepatitis. A 50-year-old woman was admitted to the hospital because of acute hepatitis A. On the 22nd hospital day, normocytic normochromic anemia without reticulocytosis was developed. A bone marrow aspirate revealed erythroid hypoplasia with a small percentage of proerythroblasts and basophilic erythroblasts, but almost complete absence of polychromatophilic and orthochromic erythroblasts. This case was diagnosed as PRCA characterized by the maturation arrest of erythropoiesis. Anemia was spontaneously recovered following marked reticulocytosis. Afterward, transient EDTA-dependent pseudothrombocytopenia developed for 3 months. The serum taken during the acute phase of clearly inhibited BFU-E colony formation. This data suggests that some humoral factor in the serum of this patient may be involved in the pathogenesis of PRCA.

Female↗