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Biomedical subjects

A Maruyama

Publications and source records attributed to A Maruyama.

At least 91 records · Page 5Linked to original sources
PubMed1994

Postadsorptive behavior of plasma proteins on poly(propylene oxide)-segmented nylon-610 surfaces and its implication in preventing contact-induced activation of platelets on these surfaces.

The influence of adsorbed plasma proteins on preventing contact-induced activation of platelets on poly(propylene oxide) (PPO)-segmented nylon-610 surfaces was investigated by monitoring changes in cytoplasmic free Ca2+ concentrations in platelets and adsorption/desorption of albumin and fibrinogen on these copolymer surfaces. Direct measurement of cytoplasmic free Ca2+ concentration in platelets in contact with copolymer surfaces was achieved by monitoring spectral changes of a fluorescent indicator dye, Fura 2. These copolymers were characterized by a surface microstructure composed of coexisting crystalline and amorphous phases. An increase in cytoplasmic free Ca2+ concentration in platelets interacting with polymer surfaces was observed, and this increase was found to be strongly reduced both by the adsorption of plasma proteins into the polymer surface and by modifying the surface microstructure of the polymer itself. Transient changes in cytoplasmic free Ca2+ concentration were observed in platelets in contact with the surface of copolymer 61P3-25, which exhibited excellent nonthrombogenicity in our previous studies, depending on the residence time of plasma and plasma concentration. Additionally, adsorption/desorption of albumin and fibrinogen on copolymer surfaces was estimated using 125I-labeled proteins. Exchange of the adsorbed albumin with fibrinogen and minimum fibrinogen adsorption were observed particularly on the 61P3-25 surface. Exchange of adsorbed fibrinogen with plasma proteins and/or increased fibrinogen adsorption were also observed on all other polymer surfaces examined. Finally, we conclude that controlled formation of a defined protein adsorption layer on the 61P3-25 surface via the transient exchange of adsorbed albumin with fibrinogen from plasma, can be a dominant factor in preventing platelet adhesion and activation on this surface.

Adsorption↗
PubMed1994

Cellular distribution of polymer particles bearing various densities of carbohydrate ligands.

The density effect of carbohydrate-ligands on nanometer-order particles (nanoparticles) upon cellular binding and internalization was investigated. Poly(vinylbenzyl-beta-D-lactonamide) (PVLA), a beta-galactose-carrying styrene homopolymer, was employed as a model ligand for the asialoglycoprotein receptors on hepatocytes. In order to control the surface ligand densities on the particles, PVLA was mixed with poly(vinylbenzyl-D-gluconamide) (PVGA), a PVLA analog without beta-galactose, and their mixtures were used as surface coatings. The particles with low ligand densities associated more with hepatocytes than high ligand density particles. The surface density of the ligand considerably influenced the cellular distribution. Most of the particles bearing high densities of ligands were found inside the cells, whereas particles with low ligand densities were found on the plasma membrane surface of the hepatocytes. These results were indicative of high densities of ligands on the surface requiring hepatocytes to internalize the particles promptly by receptor-mediated endocytosis, while low densities of ligands on the surface was not sufficient to internalize, but allowed particles to bind on the cell surface. These findings enabled us to regulate cellular distributions of particles by controlling ligand density on the surface.

Animals↗
PubMed1994

Physiological increase in plasma insulin concentration suppresses proinsulin secretion in normal controls but not in subjects with glucose intolerance.

Since insulin negatively controls its own secretion, we examined if insulin also inhibits the secretion of its precursor, proinsulin, in subjects with varying degrees of glucose tolerance. Under comparable hyperinsulinemia (50-70 microU/ml) achieved by the euglycemic insulin clamp technique, plasma C-peptide concentrations were equally suppressed to approximately 40-50% in nonobese subjects with normal glucose tolerance (NGT) (n = 13, 35.5 +/- 3.7%, M +/- SEM), borderline glucose intolerance (BGI) (n = 12, 46.7 +/- 5.6%), and non-insulin-dependent diabetes mellitus (NIDDM) (n = 12, 48.9 +/- 5.4%). In contrast, plasma proinsulin concentrations were slightly but significantly suppressed in NGT (4.1 +/- 0.2 to 3.7 +/- 0.2 pmol/L, P < 0.05), but not in patients with BGI (4.6 +/- 0.3 to 4.8 +/- 0.5 pmol/L, NS) and NIDDM (5.5 +/- 0.5 to 4.9 +/- 0.4 pmol/L, NS). The basal concentrations of proinsulin increased as glucose tolerance declined (P < 0.05 between NGT and NIDDM). These results suggest that the basal secretion of proinsulin by beta-cells seems relatively insensitive to insulin compared with C-peptide, and that the insulin-proinsulin feedback loop is disturbed in glucose-intolerant subjects. Therefore, a defective feedback inhibition of proinsulin secretion by insulin may be partly involved in the disproportionate increase of plasma proinsulin concentrations in patients with NIDDM.

Adult↗
PubMed1994

MR of pulmonary hamartoma: pathologic correlation.

We describe the magnetic resonance (MR) appearance with pathologic correlation of six pulmonary hamartomas. All six tumors showed intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Four of the six tumors showed a lobulated appearance separated by septa on precontrast T1-weighted or T2-weighted images. Gadolinium-enhanced T1-weighted images showed marked enhancement of the septa that separated the tumors into less well enhanced lobules; this was seen in all six tumors. Comparison between MR images and pathologic specimens showed that the regions with less enhancement corresponded to core cartilaginous tissue and septa; areas of marked contrast enhancement corresponded to cleft-like branching mesenchymal connective tissue that dipped into the cartilaginous core. MR images correlated well with the surgically resected tumors.

Adult↗
PubMed1994

Ultrasonography of thymoma with pathologic correlation.

Preoperative ultrasonograms of 11 surgically proved thymomas and ex vivo ultrasonograms of 3 resected specimens were compared with pathologic findings of resected specimens. Among 11 thymomas 7 appeared solid, 3 were solid with several cystic regions, and the remaining one was unilocular cystic in appearance. Cystic regions on ultrasonograms corresponded to cystic changes on pathologic specimens. Six malignant thymomas showed a typical lacy appearance on ultrasonograms, which corresponded to the lobulated configuration separated by fibrous septa shown on the pathologic specimens.

Adult↗
PubMed1993

Novel antiasthmatic agents with dual activities of thromboxane A2 synthetase inhibition and bronchodilation. 2. 4-(3-Pyridyl)-1(2H)-phthalazinones.

A series of novel 4-(3-pyridyl)-1(2H)-phthalazinone derivatives which possess dual activities of thromboxane A2 (TXA2) synthetase inhibition and bronchodilation was synthesized, and their pharmacological activities were evaluated. While the length and the bulk of 2-alkyl substituents had no influence on either activity, the 2-substituents with polar groups reduced bronchodilatory activity. Furthermore, we introduced heteroaromatic nuclei into the 4-position of the phthalazinone and found that 1-imidazolyl (13a) and 5-thiazolyl (16b and 16c) derivatives were as active as the parent 3-pyridyl compound 5b. These findings suggest that heteroaromatic nuclei at the 4-position of phthalazinones play a critical role in TXA2 synthetase inhibition. Additionally, the hydrophobicity of the compounds was found to exert a marked influence on bronchodilatory activity. These observations led to the selection of 2-ethyl-4-(3-pyridyl)-1(2H)-phthalazinone (5b) (KK-505) and 2-methyl-4-(5-thiazolyl)-1(2H)-phthalazinone (16b) (KK-562) for further studies. Although their precise mechanism of action remains unclear, this series of novel phthalazinone derivatives represents a new class of antiasthma agents with dual activities.

Animals↗
PubMed1993

Effect of acute sodium bicarbonate ingestion on excess CO2 output during incremental exercise.

The effect of bicarbonate ingestion on total excess volume of CO2 output (CO2 excess), due to bicarbonate buffering of lactic acid in exercise, was studied in eight healthy male volunteers during incremental exercise on a cycle ergometer performed after ingestion (0.3 g.kg-1 body mass) of CaCO3 (control) and NaHCO3 (alkalosis). The resting arterialized venous blood pH (P < 0.05) and bicarbonate concentration ([HCO3-]b; P < 0.01) were significantly higher in acute metabolic alkalosis [AMA; pH, 7.44 (SD 0.03); [HCO3-]b, 29.4 (SD 1.5) mmol.l-1] than in the control [pH, 7.39 (SD 0.03); [HCO3-]b, 25.5 (SD 1.0) mmol.l-1]. The blood lactate concentrations ([la-]b) during exercise below the anaerobic threshold (AT) were not affected by AMA, while significantly higher [la-]b at exhaustion [12.29 (SD 1.87) vs 9.57 (SD 2.14) mmol.l-1, P < 0.05] and at 3 min after exercise [14.41 (SD 1.75) vs 12.26 (SD 1.40) mmol.l-1, P < 0.05] were found in AMA compared with the control. The CO2 excess increased significantly from the control [3177 (SD 506) ml] to AMA [3897 (SD 381) ml; P < 0.05]. The CO2 excess per body mass was found to be significantly correlated with both the increase of [la-]b from rest to 3 min after exercise (delta[la-]b; r = 0.926, P < 0.001) and with the decrease of [HCO3-]b from rest to 3 min after exercise (delta [HCO3-]b; r = 0.872, P < 0.001), indicating that CO2 excess per body mass increased linearly with both delta [la-]b and delta [HCO3-]b.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Bone marrow transplantation for late infantile metachromatic leukodystrophy: pathogenic investigation for graft rejection.

A Japanese boy aged 2 years 11 months with late infantile metachromatic leukodystrophy underwent bone marrow transplantation (BMT) from his human leukocyte antigen (HLA) identical but mixed lymphocyte culture reactive father. Chimerism and increased arylsulfatase A activities of leukocytes had been observed with retarded progression of neurological deterioration during the first 3 months post-BMT. Graft rejection gradually occurred and donor cells were almost completely eliminated from the patient at 1 year after BMT. The process of neurodegeneration progressed clinically and neuroradiologically. Three possible reasons for the pathogenesis of graft rejection are: (i) T cell depletion of donor marrow cells as graft-versus-host disease (GVHD) prophylaxis; (ii) a slightly weak conditioning regimen: and (iii) a small number of marrow cells transplanted. It is stressed that as BMT is still a preliminary therapy for metachromatic leukodystrophy indications, conditioning, and GVHD prophylaxis for BMT should be considered individually.

Bone Marrow Transplantation↗
PubMed1993

Abundance of Virus-Sized Non-DNase-Digestible DNA (Coated DNA) in Eutrophic Seawater.

Total DNA concentration in 0.2-mum-pore-size Nuclepore filter filtrates (<0.2-mum fraction) of Tokyo Bay water was estimated to be 9 to 19 ng/ml by an immunochemical quantification method. Almost 90% of the DNA in the <0.2-mum fraction was found in the size fractions larger than 3.0 x 10 Da and 0.03 mum, and most was not susceptible to DNase digestion, that is, consisted of non-DNase-digestible DNA (coated DNA). A significant amount of DNA was obtained from the <0.2-mum fraction of the seawater by three different methods: polyethylene glycol precipitation, direct ethanol precipitation, and ultrafilter concentration. Gel electrophoresis analysis of the isolated DNAs showed that they consisted mainly of coated DNAs with a similar molecular sizes (20 to 30 kb [1.3 x 10 to 2.0 x 10 Da). The abundance of the ultramicron virus-sized coated DNA in natural seawater suggests that these DNA-rich particles can be attributed to marine DNA virus assemblages and that they may be a significant phosphorus reservoir in the environment.

Journal Article↗
PubMed1992

A new synthetic hypoglycaemic polysaccharide.

The synthetic (1-->6)-alpha-D-glucopyranan with branching and without branching were tested as a new hypoglycaemic drug. (1-->6)-alpha-D-glucopyranan having an alpha-D-glucopyranosyl branch at the C-3 position (1) showed a remarkable hypoglycaemic activity on i.p. injection to mice. The polysaccharide having both alpha- and beta-glucopyranosyl branches (2) also lowered the blood sugar (glucose) level in mice. On the other hand, the synthetic linear (1-->6)-alpha-D-glucopyranan (3) and alpha-D-glucopyranosyl branched polysaccharide (4) did not have a hypoglycaemic function, indicating that the branching glucose units are essential for the biological activity.

Animals↗
PubMed1992

Effect of endurance training on excessive CO2 expiration due to lactate production in exercise.

We attempted to determine the change in total excess volume of CO2 output (CO2 excess) due to bicarbonate buffering of lactic acid produced in exercise due to endurance training for approximately 2 months and to assess the relationship between the changes of CO2 excess and distance-running performance. Six male endurance runners, aged 19-22 years, were subjects. Maximal oxygen uptake (VO2max), oxygen uptake (VO2) at anaerobic threshold (AT), CO2 excess and blood lactate concentration were measured during incremental exercise on a cycle ergometer and 12-min exhausting running performance (12-min ERP) was also measured on the track before and after endurance training. The absolute magnitudes in the improvement due to training for CO2 excess per unit of body mass per unit of blood lactate accumulation (delta la-) in exercise (CO2 excess.mass-1.delta la-), 12-min ERP, VO2 at AT (AT-VO2) and VO2max on average were 0.8 ml.kg-1.l-1.mmol-1, 97.8 m, 4.4 ml.kg-1. min-1 and 7.3 ml.kg-1.min-1, respectively. The percentage change in CO2 excess.mass-1.delta la- (15.7%) was almost same as those of VO2max (13.7%) and AT-VO2 (13.2%). It was found to be a high correlation between the absolute amount of change in CO2 excess.mass-1.delta la-, and the absolute amount of change in AT-VO2 (r = 0.94, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Thin-rim enhancement in Gd-DTPA-enhanced magnetic resonance images of tuberculoma: a new finding of potential differential diagnostic importance.

The article describes rim enhancement seen on Gd-DTPA-enhanced magnetic resonance (MR) images of two patients with tuberculoma. Pathologic examination of the surgical specimens disclosed that the peripheral portion of the tuberculoma, which showed contrast enhancement, was composed mainly of a fibrous capsule and epithelioid granulomas and that the central zone, which showed no contrast enhancement, was composed of caseous necrotic material. In a retrospective study of MR images from 20 consecutive cases of surgically proven bronchogenic carcinoma, none showed a thin enhancing rim on postcontrast MR images. Although confirmation of these findings must await further experience, the postcontrast MR findings described here may prove to be of value in distinguishing tuberculoma and possibly other granulomatous lesions from bronchogenic carcinoma.

Adult↗
PubMed1992

MR imaging of thymoma: radiologic-pathologic correlation.

MR images in 17 patients with surgically proved thymomas (12 malignant and five benign) were reviewed and compared with pathologic specimens. In nine cases, MR images of excised specimens also were made and evaluated. On T2-weighted images, 11 of 12 malignant thymomas had an inhomogeneous signal intensity, half with and half without a lobulated internal architecture. None of the five benign thymomas had a lobulated internal architecture, and they all had a moderately or slightly inhomogeneous signal. Cystic regions and/or hemorrhage were noted pathologically, and corresponded to areas of inhomogeneous high signal intensity seen on T2-weighted images. Examination of the excised specimens in malignant thymomas showed that the lobulated configuration seen in the tumors was caused by thick fibrous septa. Our experience suggests that, although calcification cannot be identified, MR is helpful in making a differential diagnosis of mediastinal tumors and in determining malignancy of thymoma.

Adult↗
PubMed1992

Intrathoracic neurogenic tumors: MR-pathologic correlation.

An MR-pathologic correlation of nine intrathoracic neurogenic tumors (three neurofibromas, four schwannomas, and two ganglioneuromas) was performed to characterize their MR appearances. The three types of intrathoracic neurogenic tumor were found to have characteristic appearances on MR images that should be helpful when establishing the differential diagnosis of posterior mediastinal tumors. The MR and histologic features of these tumors are illustrated and described in this essay.

Adolescent↗
PubMed1991

Synthesis and evaluation of antiinflammatory activities of a series of corticosteroid 17 alpha-esters containing a functional group.

A series of 21-desoxy-21-chlorocorticosteroids that contain a functionalized ester group at 17 alpha has been prepared and examined to separate their systemic activity from topical antiinflammatory activity. Introduction of the functionalized ester group at 17 alpha was carried out by an acid-catalyzed formation of cyclic ortho esters with 17 alpha,21-hydroxyl groups of corticosteroids and subsequent acid-catalyzed hydrolysis. As for the functional group, chloro, methoxy, acetoxy, cyano, cyclopropyl, or alkoxycarbonyl group was introduced at the terminal carbon atom of the 17 alpha-alkanoate group. The topical antiinflammatory activity and systemic activity of these compounds were examined and found to be significantly dependent on the functionalities in the 17 alpha-esters. Among these derivatives, a series of 17 alpha-(alkoxycarbonyl)alkanoates (17 alpha-OCO(CH2)nCOOR) showed an excellent separation of the systemic activity from topical activity. The effects of the number of methylene groups (n) and of the alkyl groups of the ester (R) on either topical or systemic activity of the corticosteroid derivatives were also investigated.

Administration, Topical↗
PubMed1991

[Immunologic function against infection in splenic autotransplanted mice].

The increasing recognition of the danger of overwhelming postsplenectomy infection (OPSI) has led surgeons to attempt to maintain splenic function after spleen injury. One technique they use when splenorrhapy or partial splenectomy are not feasible is the deliberate autotransplantation of splenic tissue. But the amount of splenic tissue necessary to prevent OPSI remains controversial, and opinions differ about the importance of the location and size of the splenic fragments implanted. The mice were divided into five groups, I. splenectomy, II. splenectomy +30% of the spleen implanted intraperitoneal site, III. splenectomy +50% implanted intraperitoneally, IV. splenectomy +50% implanted subcutaneously and V. Sham operation. This study assessed the blood flow of the splenic tissue, increasing weight of splenic mass, histology, the serum level of the immunoglobulins (IgG, IgA, and IgM), pneumococcal antibody titers after vaccination, and survival after intravenous pneumococcal challenge. This study demonstrated that intraperitoneal transplantation showed better regeneration and afforded better protection from OPSI than subcutaneous transplantation. And 30 to 50 percent of the whole splenic tissue mass protected against experimental pneumococcal sepsis. The splenic autotransplants developed in volume and blood supply after 8 weeks, and immunologic function against infection recovered at the same time.

Animals↗
PubMed1991

[Two cases of idiopathic pneumopericardium].

Idiopathic pneumopericardium (I.P.) is a rare disease which occurs in a manner etiologically different from pneumopericardium. Recently, we encountered two apparent cases of I.P. at the Department of Surgery, Aomori Rhosai Hospital. Results of observation indicated that, in case 1, diving practice in a pool was the cause of the sickness, and in case 2, the cause was severe morning sickness during pregnancy. Unlike pneumopericardium that comes from traumatism, lesions of the surrounding organs, infection iatrogenicity and the like, the present cases were diagnosed as idiopathic pneumopericardium resulting from rupture of a number of alveoli due to transitory abnormal increase in Valsalva maneuver at expiration.

Adolescent↗