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Biomedical subjects

T Masuzawa

Publications and source records attributed to T Masuzawa.

At least 127 records · Page 7Linked to original sources
PubMed1994

Experimental induction of Lyme arthritis in outbred mice.

Outbred ddY mice inoculated with live cells of Borrelia burgdorferi strain 297 into hind footpad displayed swelling of the footpad at days 7 to 11 after inoculation. Marked neutrophilic infiltration was observed in the subcutaneous tissue and the part of bone tissue which was partially destroyed, and synovial layer of articular capsule was thickened and protruded into the joint space in the histopathological examination of footpad inoculated with live Borrelia cells. The inflammation peaked at day 7 and B. burgdorferi was cultured from bladder and heart of the mice at day 14 after inoculation. The mice inoculated with heat-inactivated cells at 56 C for 30 min did not show any significant histopathological change. In this mice model, nontreated littermates were not infected in contact with infected littermates for 14 days of experimental period. The outbred ddY mice model is useful for evaluating the effectiveness of vaccination against Lyme disease.

Animals↗
PubMed1994

Characterization of monoclonal antibodies for identification of Borrelia japonica, isolates from Ixodes ovatus.

Monoclonal antibodies for identification of Borrelia japonica isolated from tick, Ixodes ovatus and long-tailed shrew, Sorex unguiculatus in Japan and Borrelia related to Lyme disease (Borrelia burgdorferi sensu lato) were prepared and characterized. All isolates belonging to B. japonica and isolates from I. dentatus and cottontail rabbit in North America reacted with MAb O1441b against flagellin which was prepared from immunized mice with strain HO14, type strain of B. japonica, but isolates from I. persulcatus, patient, and wood mouse, Apodemus speciosus ainu, in Japan, and isolates belonging to B. burgdorferi, B. garinii and B. afzelii from North America and Europe did not. Strains used in this study reacted with MAb P62 against common antigen which was prepared from immunized mice with strain NT24 isolated from I. persulcatus in Japan, but B. japonica did not. These MAbs are useful for identification and differentiation of B. japonica and B. burgdorferi sensu lato in Japan.

Animals↗
PubMed1994

In vitro antibiotic susceptibilities of Borrelia isolates from erythema migrans lesion of Lyme disease patients in Japan.

Antibiotic susceptibilities of twelve borrelial isolates from skin of patients with erythema migrans (EM) and ticks (Ixodes persulcatus and I. ovatus) in Japan were examined by in vitro microdilution MIC method and macrodilution MBC method. Nine EM isolates and 3 tick isolates were susceptible to amoxicillin, erythromycin, and minocycline. MICs for Japanese isolates were 0.038-0.30 microgram/ml, < 0.012 microgram/ml, and < 0.012-0.05 microgram/ml, respectively. MBCs were as follows: 0.038-0.88 microgram/ml, < 0.012-0.10 microgram/ml, and < 0.025-0.78 microgram/ml, respectively. These antibiotics could be recommended for treatment of patients in early stage of Lyme disease in Japan.

Amoxicillin↗
PubMed1994

Polymerase chain reaction analysis of Borrelia species isolated in Japan.

Primer reactivities of 25 Borrelia burgdorferi sensu lato isolates from the ticks, Ixodes persulcatus and I. ovatus, in Japan and 10 isolates in Europe and North America were investigated. The methods used in this study were the polymerase chain reaction (PCR) on the flagellin structural gene (fla), the outer surface protein A gene (osp A) and the outer surface protein B gene (osp B), and the restriction fragment length polymorphism (RFLP) analysis of PCR products from osp A and osp B. The flagellin PCR primer set reacted with all the Borrelia strains tested. Four genospecies, B. burgdorferi sensu stricto, B. garinii, B. afzelii and B. japonica, were differentiated by PCR using osp A and osp B primers combined with RFLP analysis. Some Japanese isolates from I. persulcatus were identified as B. garinii or B. afzelii. The other isolates from I. persulcatus did not fit in any of the 4 genospecies. These results suggested that Japanese isolates from I. persulcatus are highly heterogeneous in their osp A and osp B structures. Furthermore, PCR primers targeting fla are applicable to the gene diagnosis for Lyme disease in Japan, and osp A and osp B primers can be used to classify B. burgdorferi sensu lato isolates into genospecies by PCR and RFLP analyses.

Bacterial Outer Membrane Proteins↗
PubMed1994

Infectivity and early antibody response to Borrelia burgdorferi sensu lato isolated in Japan in outbred mice.

Borrelia burgdorferi sensu lato isolated from Ixodes ovatus (B. japonica), I. persulcatus and patients with erythema migrans (EM) in Japan were determined on infectivity and arthritis induction-activity in outbred mice. Infectivity of B. japonica was weak and did not induce the development of footpad swelling by subcutaneous (s.c.) inoculation into the footpad. Challenged strain, NO129-M of B. japonica, to ddY mice were reinoculated to the mice at various cell numbers (1 x 10-1 x 10(6) cells/mouse). The strain isolated from the mouse did not reinfect ddY mice and did not induce the production of specific antibody to the homologous strain. On the other hand, strains from I. persulcatus and patients with EM in Japan infected the mice and induced a serious inflammatory response in Borrelia-inoculated footpad as well as strains belonging to the three genospecies, B. burgdorferi sensu stricto, B. garinii, and B. afzelii, related to Lyme disease, from North America and Europe. The mice were infected with 10 cells of strain HP1 isolated from I. persulcatus in Hokkaido and of strain 297 isolated from a patient in the U.S.A. by subcutaneous inoculation into the hind footpad, or by intradermal inoculation into the back. Antigens of ca. 20, 23-24 (Osp C), 29, 39, 41 (flagellin) and 45 kDa reacted with the pooled sera from mice inoculated with strains HP1 and 297, but Osp A and Osp B did not.

Animals↗
PubMed1994

A flow visualization study of the NCVC centrifugal blood pump.

A compact centrifugal pump, NCVC-1, has an open-type impeller with 6 curved vanes, and it is characterized by no shaft and no seal. A tunnel is placed in the center of the impeller-rotor assembly to irrigate the back space behind the rotor. To evaluate the flow, we performed 3 visualization methods: tracer, oil film, and injection streak line method. The flow, observed by the tracer method in NCVC-1, indicated little turbulence along vanes. A volute chamber proved effective to reduce vortex formation in the outlet. Oil film pattern revealed no flow separation on vanes at 5 L/min. Washout flow behind the rotor is essential to prevent thrombus formation and was shown as inward spiral flow without any stagnation. These data suggested that a combination of visualization techniques was useful to analyze various flow conditions, and the NCVC-1 has excellent flow characteristics with little turbulence and little flow stagnation, which must be beneficial to low hemolysis and high antithrombogenicity.

Heart-Assist Devices↗
PubMed1994

Ca(2+)-dependent non-NMDA receptor-mediated synaptic currents in ischemic CA1 hippocampal neurons.

1. The changes in excitatory postsynaptic currents (EPSCs) after transient cerebral ischemia were studied using whole-cell recording from CA1 pyramidal neurons in gerbils. In 64% (18 of 28) neurons recorded 1.5-3 days after ischemia, EPSCs showed a markedly slowed time course that was never seen in normal control neurons. 2. The slow EPSCs were not affected by an N-methyl-D-aspartate (NMDA) receptor antagonist [DL-2-aminophosphonovalerate (APV); 100 microM] but were abolished by a non-NMDA receptor antagonist [6-cyano-7-nitroquinoxaline-2,3-dione (CNQX); 10 microM], indicating that the slow EPSCs were mostly composed of non-NMDA current. 3. The slow non-NMDA EPSCs had rise times ranging from 1.2 to 7.3 ms and decay time constants between 11.5 and 56.3 ms. In normal neurons the rise time of the non-NMDA component of EPSCs ranged from 1.6 to 7.5 ms and the decay time constants ranged from 4.9 to 27.3 ms. 4. The reversal potential of the slow EPSCs in ischemic neurons was not changed by replacing 50% of the NaCl in the external solution with sodium isethionate. Bath application of 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid (SITS; 100 microM) had no effect on the slow EPSCs. Therefore Cl- current is not responsible for the slow EPSCs. 5. When external Ca2+ concentration was reduced to half of control, the decay time constant of the slow EPSCs decreased to 50 +/- 25%, mean +/- SD. In addition, bath application of a cell-permeable Ca2+ chelator, 1,2-bis(o-aminophenoxy)ethane-N,N,-N',N'-tetraacetyl,tetr aacetoxymethyl ester(BAPTA-AM), reduced the decay time constant.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Estrogen deficiency stimulates B lymphopoiesis in mouse bone marrow.

We have found that an estrogen deficiency causes a marked increase in bone marrow cells. To examine the effect of estrogen on hemopoiesis, we characterized the increased population of bone marrow cells after ovariectomy (OVX). In OVX mice, the percentage of myeloid cells and granulocytes was decreased, whereas that of B220-positive B lymphocytes was selectively increased 2-4 wk after surgery. The total number of myeloid cells and granulocytes did not change appreciably, but that of B220-positive cells was greatly increased by OVX. When OVX mice were treated with estrogen, the increased B lymphopoiesis returned to normal. B220-positive cells were classified into two subpopulations, B220low and B220high. The majority of the B220low cells were negative for the IgM mu chain, whereas most of the B220high cells were mu-positive. OVX selectively increased the precursors of B lymphocytes identified by B220low. mu-negative phenotype, suggesting that an estrogen deficiency stimulates accumulation of B lymphocyte precursors. When bone marrow-derived stromal cells (ST2) were pretreated with estrogen then co-cultured with bone marrow cells in the presence of estrogen, the stromal cell-dependent B lymphopoiesis was greatly inhibited. The present study suggests that estrogen plays an important role in the regulation of B lymphocyte development in mouse bone marrow.

Animals↗
PubMed1994

Relationship between cytosolic Ca2+ level and contractile tension in canine basilar artery of chronic vasospasm.

In order to study the role of the Ca2+/calmodulin/myosin light chain kinase system in the development of chronic vasospasm caused by subarachnoid hemorrhage, the cytosolic Ca2+ level ([Ca2+]i), measured with fura-2, a fluorescent Ca2+ indicator, and contractile tension were measured simultaneously, and their quantitative correlation was examined in basilar arterial tissue obtained from the canine "two-hemorrhage" model. Sixteen adult mongrel dogs were divided into two groups, control (n = 8) and vasospasm (n = 8), and were killed 7 days after the first experimental subarachnoid hemorrhage. In basilar arterial tissue loaded with fura-2, 1) [Ca2+]i in the resting condition was not significantly different between the two groups; 2) the increment in [Ca2+]i induced by 40 mmol/L K+ stimulation was significantly smaller in vasospastic tissue (P < 0.01); and 3) 40 mmol/L K(+)-induced tension development per cross-sectional area for a fixed increment in [Ca2+]i was significantly greater in vasospastic tissue (P < 0.01). In tissue not loaded with fura-2, active myogenic tone, which was tentatively represented by the ratio of tonus relaxed with 10(-4) mol/L papaverine to initial resting tone, was significantly greater in vasospastic tissue (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

DNA strand-breaking activities of quinolone antimicrobial agents under visible light irradiation.

The DNA strand-breaking activities of 9 quinolones, widely used as antimicrobial agents and suspected to induce photo-dermatological disorders in humans, were examined under irradiation using standard domestic fluorescent lamps. Two quinolones, tosufloxacin and enoxacin, converted the supercoiled covalently closed circular plasmid DNA to the open circular form under visible light irradiation. The maximum of photodynamic single strand-breaking activity for tosufloxacin was found to be 12% at 50 microM and that of enoxacin was 33% at a concentration of 2 mM. The DNA strand-breaking activities of photoirradiated tosufloxacin and enoxacin were markedly inhibited by NaN3 but only partially by D-mannitol, superoxide dismutase (SOD) and catalase did not inhibit these activities. These results suggest that some quinolone antimicrobial agents can be activated by visible light and induce phototoxic DNA damage in various organisms. We should carefully investigate such phototoxic activities during the development of new quinolones to avoid producing phototoxic disorders in man.

4-Quinolones↗
PubMed1994

Lyme disease spirochetes in a wild fox (Vulpes vulpes schrencki) and in ticks.

Lyme disease spirochetes were demonstrated in a wild female fox (Vulpes vulpes schrencki) and in Ixodes persulcatus ticks collected from the fox on Sapporo, Hokkaido, Japan. Spirochetes were detected in I. persulcatus, as well as skin lesions, brain, heart, kidney, and liver of the fox. Five of seven isolates reacted with a monoclonal antibody against Borrelia afzelii specific Osp B. Deoxyribonucleic acid (DNA) relatedness of a brain isolate was 89% to B. afzelii, and ranged from 50 to 67% to three other species. Immunoglobulin G antibodies to B. afzelii, B. garinii and B. burgdorferi sensulato, when tested in an enzyme-linked immunosorbent assay (ELISA), were negative in the fox. There were no antibodies against seven serovars of Leptospira interrogans.

Animals↗
PubMed1994

[Rhinogenous retrobulbar optic neuritis: a case report].

Rhinogenous retrobulbar optic neuritis is characterized by neuritis secondary to paranasal sinusitis. A case of rhinogenous retrobulbar optic neuritis that was successfully treated by surgery is reported. A 40-year-old man complained of progressive right visual disturbance. The clinical course and neurological examination suggested right retrobulbar optic neuritis. CT and MRI scans demonstrated a massive tumor-like lesion near the right optic canal. Fifteen days after the onset, decompression of the right optic nerve was performed using a right pterional approach. After surgery, visual disturbance improved, and after about 1 month, the symptom had disappeared. Operative findings, histological examination and the postoperative course were consistent with the characteristics of rhinogenous retrobulbar optic neuritis. We consider decompression of the optic nerve to be effective for the treatment of rhinogenous retrobulbar optic neuritis.

Adult↗
PubMed1993

The capacity of central and peripheral catecholaminergic neurons to innervate the pineal organ and cerebral cortex of the rat: in vitro immunohistochemical observations.

The locus coeruleus (LC) or superior cervical ganglion (SCG) of neonatal rats were co-cultured either with the pineal organ or cerebral cortex (CX) to investigate the innervating capacity of central and peripheral catecholamine neurons under these experimental conditions. After 2 weeks of co-culturing, cultures were fixed for tyrosine hydroxylase (TH) immunohistochemistry to examine the distribution of catecholamine neurons and their fibers. Glial fibrillary acidic protein and fibronectin immunohistochemistry was performed to determine the cell types proliferating around the explants. In LC/CX co-cultures, numerous astrocytes spread between the two explants, and TH-immunoreactive neurites were generally seen to invade CX explants. In contrast, neurite extension from LC to pineal explants occurred only when a glial cell sheet grew between the two explants, and when the pineal explants were not surrounded by a tight fibronectin-positive cell layer. Neurites of the SCG usually invaded both CX and pineal explants, regardless of the existence of glial or non-glial cell layer. These results indicate that central and peripheral catecholamine neurites have the potential of invading both the cortex and pineal, although they are distributed only in particular regions of the intact brain. The distribution of LC neurites, however, seems to be profoundly affected by the cell types spreading around the explants; glial cells appear to support LC neurite extension, whereas non-glial cells appear to inhibit it.

Animals↗
PubMed1993

Magnetic resonance imaging of ganglion cell tumours.

The MRI and CT studies of four patients with ganglion cell tumours, one with a cerebellar gangliocytoma (Lhermitte-Duclos disease), and three with gangliogliomas are reported. MRI in Lhermitte-Duclos disease clearly demonstrated a mass of low signal intensity in the left cerebellum on T1-weighted spin-echo (SE) images and an area of high signal intensity with a blurred margin on T2-weighted SE images. These MRI studies were useful for delineating the lesion, which was verified at surgery. In the ganglioglioma, MRI demonstrated two isointense solid masses on T1-weighted SE images, which enhanced clearly with Gd-DTPA. The enhancement study was advantageous in planning surgery.

Adolescent↗
PubMed1993

Genomic analysis of Borrelia japonica sp. nov. isolated from Ixodes ovatus in Japan.

Genetic characteristics of 12 Borrelia isolates from the tick, Ixodes ovatus, I. persulcatus, and the rodent, Apodemus speciosus ainu, in Japan were compared to members of the three genospecies of Borrelia burgdorferi sensu lato; B. burgdorferi sensu stricto, B. garinii and group VS461. The methods used in this study were the quantitative microplate DNA hybridization assay and restriction fragment length polymorphism (RFLP) analyses of the flagellin structural genes and the 16S rRNA genes. The six isolates from I. persulcatus and A. speciosus ainu were identified as genospecies B. garinii using RFLP analysis of the flagellin and 16S rRNA genes. In contrast, RFLP analysis of the six isolates from I. ovatus indicated that they were different from the three reported genospecies. DNA homology studies confirmed the RFLP results. The six isolates from I. ovatus had DNA homologies ranging from 85 to 99%, whereas DNA relatedness of the I. ovatus isolate with strains belonging to the three genospecies was 50 to 64%. These results suggest that the strains isolated from I. ovatus in Japan differ from the three genospecies and should be classified as a new genospecies of B. burgdorferi sensu lato. We propose that strains isolated from I. ovatus should be classified as B. japonica sp. nov.

Animals↗
PubMed1993

Protective activity of antisera against isolates of Borrelia burgdorferi from various geographical origins.

Antisera from rabbits immunized with two Japanese strains of Borrelia burgdorferi, HP3 an isolate from Ixodes persulcatus and HO14 an isolate from I. ovatus, or the European strain P/Bi isolated from human cerebrospinal fluid (CSF) did not passively protect hamsters from challenge with the infectious strain 297, a North American isolate from patient CSF. Antisera to strains 297 and B31, a North American isolate from I. dammini, however, provided protective effect to challenge with strain 297. Immune mice sera in the presence of homologous B. burgdorferi antigen induced the production of oxygen intermediates from mouse peritoneal exudate cells. Heterologous B. burgdorferi antigen had no effect. These results suggest that antigenic properties of Japanese strains are different from those of North American and European isolates.

Animals↗
PubMed1993

A flow visualization study of centrifugal blood pumps developed for long-term usage.

We have developed centrifugal pumps for long-term circulatory assistance, with the final goal of a completely implantable ventricular assist device or total artificial heart. The previous model, NCVC-0, was characterized by a nonseal design and few flow-stagnating parts and acquired high durability and antithrombogenicity. To improve its pumping performance, NCVC-0 was modified. In the new model, NCVC-1, the profile shape of the impeller was changed from flat to conical, the number of vanes from 4 to 6, and the vane entrance angle from 30 degrees to 60 degrees. A flow visualization study performed by means of a combination of the polystyrene tracer method and the light-cutting method indicated decreased flow turbulence between vanes in NCVC-1, which corresponded well with the increased pumping performance. Flow visualization is a useful method to evaluate the design elements that are closely related to the pumping performance of a centrifugal blood pump.

Equipment Design↗