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T Masuzawa

Publications and source records attributed to T Masuzawa.

At least 19 recordsLinked to original sources
PubMed2006

Widespread distribution and high prevalence of an alpha-proteobacterial symbiont in the tick Ixodes ricinus.

The tick Ixodes ricinus is responsible for the transmission of a number of bacterial, protozoan and viral diseases to humans and animals in Europe and Northern Africa. Female I. ricinus from England, Switzerland and Italy have been found to harbour an intracellular alpha-proteobacterium, designated IricES1, within the cells of the ovary. IricES1 is the only prokaryote known to exist within the mitochondria of any animal or multicellular organism. To further examine the distribution, prevalence and mode of transmission of IricES1, we performed polymerase chain reaction screening of I. ricinus adults from 12 countries across its geographic distribution, including tick colonies that have been maintained in the laboratory for varying periods of time. IricES1 was detected in 100% of field-collected female ticks from all countries examined (n = 128), while 44% of males were found to be infected (n = 108). Those males that are infected appear to harbour fewer bacteria than females. Sequencing of fragments of the 16S rRNA and gyrB genes revealed very low nucleotide diversity among various populations of IricES1. Transmission of IricES1 from engorged adult females to eggs was found to be 100% (n = 31). In tick colonies that had been maintained in the laboratory for several years, a relatively low prevalence was found in females (32%; n = 25). To our knowledge, IricES1 is the most widespread and highly prevalent of any tick-associated symbiont.

Alphaproteobacteria↗
PubMed2005

Seroepidemiology of Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum in wild mice captured in northern Turkey.

An expedition across the Asian part of the Black Sea coast and national parks of Northern Turkey was organized in the summer of 2001 to investigate the presence of Borrelia burgdorferi sensu lato (s.l.), Lyme borreliosis agent, and Anaplasma phagocytophilum, human granulocytic ehrlichiosis, agent, in wild mice. A total of 65 Apodemus flavicollis, Apodemus sylvaticus, Microtus epiroticus, Crocidura suaveolens and Mus macedonicus, were captured. Two out of 22 Apodemus sylvaticus specimens were seropositive for B. afzelii by enzyme-linked immunosorbent assay as confirmed by Western blotting, however cultures of skin and bladder samples from all small mammals in Barbour-Stoenner-Kelly's medium-II remained negative for B. burgdorferi s.l. All sera tested were negative for Anaplasma phagocytophilum by indirect immunofluorescent assay. The prevalence of B. burgdorferi s.l. and Anaplasma phagocytophilum is low in wild mice of the Asian part of Northern Turkey.

Anaplasma phagocytophilum↗
PubMed2003

Enhancement of thymidine kinase-mediated killing of malignant glioma by BimS, a BH3-only cell death activator.

Herpes simplex virus thymidine kinase (HSV-tk)/gancyclovir (GCV) therapy has the ability to inhibit tumor formation in animal models but the results of clinical trials have been disappointing. To improve the performance of tk/GCV therapy, we tried combination therapy designed to enhance its cytotoxic effects by introducing genes that induce apoptosis of the tumor cells through different pathways. We concentrated our efforts on the use of Bim, a BH3-only member of death activators in the Bcl-2 superfamily, because Bim is not involved in the pathways through which HSV-tk/GCV therapy induces apoptosis in malignant glioma cells. Among three alternative splicing variants, BimEL, BimL, and BimS, BimS lacks the binding domain for the dynein light chain LC8, which negatively regulates the proapoptotic function of BimEL and BimL. All four malignant glioma cell lines, U251, A172, T-430, and U373 underwent cell death after transfer of BimS using an adenovirus vector (AVC2). Intriguingly, combination of AVC2-BimS with AVC2-tk markedly increased the sensitivity of U251 cells to GCV both in vitro and in vivo. In contrast, AVC2-BimL did not induce significant cell death. These results indicated that BimS had the ability to improve the efficiency of HSV-tk/GCV therapy in the treatment of malignant glioma and suggested that the targeting of different proapoptotic pathways may be a useful strategy for the development of an effective gene therapy approach to treatment.

Adenoviridae↗
PubMed2001

Modulation of synaptic transmission in hippocampal CA1 neurons by a novel neurotoxin (beta-pompilidotoxin) derived from wasp venom.

We examined the effects of beta-pompilidotoxin (beta-PMTX), a neurotoxin derived from wasp venom, on synaptic transmission in the mammalian central nervous system (CNS). Using hippocampal slice preparations of rodents, we made both extracellular and intracellular recordings from the CA1 pyramidal neurons in response to stimulation of the Schaffer collateral/commissural fibers. Application of 5-10 microM beta-PMTX enhanced excitatory postsynaptic potentials (EPSPs) but suppressed the fast component of the inhibitory postsynaptic potentials (IPSPs). In the presence of 10 microM bicuculline, beta-PMTX potentiated EPSPs that were composed of both non-NMDA and NMDA receptor-mediated potentials. Potentiation of EPSPs was originated by repetitive firings of the presynaptic axons, causing summation of EPSPs. In the presence of 10 microM CNQX and 50 microM APV, beta-PMTX suppressed GABA(A) receptor-mediated fast IPSPs but retained GABA(B) receptor-mediated slow IPSPs. Our results suggest that beta-PMTX facilitates excitatory synaptic transmission by a presynaptic mechanism and that it causes overexcitation followed by block of the activity of some population of interneurons which regulate the activity of GABA(A) receptors.

2-Amino-5-phosphonovalerate↗
PubMed2001

Transient cheiro-oral syndrome due to a ruptured intracranial dermoid cyst.

We present here a case of episodic, pure cheiro-oral syndrome caused by a ruptured intracranial dermoid cyst. Cranial magnetic resonance imaging (MRI) using the fat-suppression method revealed a fatty mass lesion in the subarachnoid space of the left parasellar region and multiple lipid droplets in the subarachnoid space over the left perisylvian area. Although no evidence for it pathogenesis was obtained, the patient's cheiro-oral syndrome could have resulted from a transient vasospasm around the left ventral posterior thalamic nucleus or postcentral gyrus.

Adolescent↗
PubMed2001

Vaccination with MCP-1 cDNA transfectant on human malignant glioma in nude mice induces migration of monocytes and NK cells to the tumor.

Recently, studies on vaccination with tumor cells genetically engineered to produce monocyte chemoattractant protein-1 (MCP-1) have provided some encouragement. These studies have shown infiltration of certain types of lymphocytes at the tumor site. However, natural killer (NK) cells have not yet been assessed. We obtained a human malignant glioma cell line producing human MCP-1 constitutively by transfection of MCP-1 cDNA. We then test the effect of vaccination with the MCP-1 transfectant on nude mice. Although vaccination with MCP-1 transfectant did not reduce the tumor in our study, it was associated with the infiltration of large numbers of NK cells and monocytes at the tumor site. The site of vaccination also showed large numbers of monocytes. NK cells were detected with anti-asialo GM1 antibody, and monocytes were detected immunohistochemically with F4/80. We assumed that infiltrating monocytes at the site of vaccination could promote the infiltration of monocytes and NK cells into the tumor site without T-cell mediated transduction because the host lacked T-cell function.

Animals↗
PubMed2001

An ultradurable and compact rotary blood pump with a magnetically suspended impeller in the radial direction.

A magnetically suspended centrifugal blood pump has been developed with a self-bearing motor for long-term ventricular assist systems. The rotor of the self-bearing motor is not only actively suspended in the radial direction, but also is rotated by an electromagnetic field. The pump has a long lifetime because there are no mechanical parts such as seals and motor bearings. An outer rotor mechanism was adopted for the self-bearing motor. The stator was constructed in the central space of the motor. The rotor shaped thin ring was set at the circumferential space of the stator. Six vanes were extended from the upper surface of the rotor toward the center of the pump to construct an open-type impeller. The outer diameter and the height of the impeller are 63 mm and 34 mm, respectively. The magnetic bearing method and the servomotor mechanism were adopted to levitate and rotate the rotor. Radial movements of the rotor and rotation are controlled actively by using electromagnets in the stator. Axial movement and tilt of the rotor are restricted by passive stability to simplify the control. The radial gap between the rotor and the stator is 1 mm. A closed-loop circuit filled with water was used to examine basic performance of the pump. Maximum flow rate and pressure head were 8 L/min and 200 mm Hg, respectively. Maximum amplitude of radial displacement of the impeller was 0.15 mm. The impeller could be suspended completely without touching the casing wall during the entire pumping process. Power consumption of the pump was only 9.5 W to produce a flow rate of 5 L/min against a pressure head of 100 mm Hg. We conclude that the pump has sufficient performance for the implantable ventricular assist system.

Computer Simulation↗
PubMed2001

Borrelia sinica sp. nov., a lyme disease-related Borrelia species isolated in China.

A survey was performed for Lyme disease borrelia in the southern part of China, in Zhejiang, Sichuan and Anhui provinces, along the Yangtze River valley, in May of 1997 and 1998. Twenty isolates from Ixodes granulatus, Ixodes ovatus, Apodemus agrarius and Niviventer confucianus were obtained. These isolates were characterized by RFLP of the 5S-23S rDNA intergenic spacer, sequence analysis of the intergenic spacer, 16S rDNA and flagellin gene, DNA-DNA hybridization analysis, SDS-PAGE and Western blotting with mAbs. Six isolates from A. agrarius, five from I. granulatus collected in Zhejiang province and one from N. confucianus in Sichuan province were highly similar to strains 10MT and 5MT isolated in Korea and classified as Borrelia valaisiana. Four isolates from A. agrarius and I. granulatus collected in Zhejiang province generated unique RFLP patterns and phylogenetic analysis of the 16S rDNA and flagellin gene sequences suggested that the isolates should be classified as B. valaisiana. Furthermore, three isolates (CMN1a, CNM2, CMN3T) from N. confucianus captured in Sichuan province and one (CWO1) from I. ovatus in Anhui province showed lower 165 rDNA sequence similarity (less than 99.0%) to sequences of previously described Lyme disease-related Borrelia species. DNA-DNA hybridization results revealed that strains CMN3T and CMN1a were clearly distinct from all other known Lyme disease Borrelia species. Electron microscope observation showed the spirochaetes to be morphologically similar to those of Borrelia, but the cells contained only four periplasmic flagella inserted at each end of the spirochaetes. Based on these results, a new Borrelia species, Borrelia sinica sp. nov., is proposed. Strain CMN3T is the type strain of this new species.

Animals↗
PubMed2001

Serological analysis of human leptospirosis in the Philippines.

Leptospirosis in the Philippines is an underrepresented disease. To achieve an accurate means of serodiagnosis, we demonstrated antibodies to the prevalent Leptospira serovars in sera of 71 patients from three major hospitals in Manila by the microscopic agglutination test and Western blot analysis. Sera of 53 patients contained antibody against 8 serovars poi, tarassovi, manilae, pyrogenes, australis, grippotyphosa, javanica, and autumnalis.

Adult↗
PubMed2001

First records of tick-borne pathogens, Borrelia, and spotted fever group Rickettsiae in Okinawajima Island, Japan.

In early April 2000, tick-borne pathogens were surveyed in the northern area of Okinawajima Island, Okinawa Prefecture, which is the southernmost area of Japan. Borrelia valaisiana, a Lyme disease spirochete, was isolated from a field mouse Mus calori, and unidentified rickettsiae of the spotted fever group were isolated from all stages of Amblyomma testudinarium. These are the first reports of these pathogens on Okinawajima Island.

Animals↗
PubMed2001

Negative incidence of Lyme disease-related Borrelia spp. in Alishan, Taiwan.

To investigate the prevalence of Lyme disease-related Borrelia species, wild rodents were captured around Yushan National Park and Alishan Forest Recreation Area Park in Taiwan 2,000 to 3,000 meters above sea level. Borrelia was not isolated from 67 small mammals of 7 species. Sera from rodents showed no positive reactivity against whole cell antigens of B. garinii, B. afzelii or B. valaisiana by ELISA. These results suggested that Lyme disease is not endemic to the Alishan area.

Animals↗
PubMed2001

Lyme disease Borrelia spp. in ticks and rodents from northwestern China.

In May 1999, field surveys of Lyme disease spirochetes were conducted around the Tianshan Mountains in Xinjiang Uygur Autonomous Region in northwestern People's Republic of China. Ixodes persulcatus ticks were obtained in a Tianchi Lake valley with primary forest, while the tick fauna was poor in the semidesert or at higher altitudes in this region. Species identities were confirmed by molecular analysis in which an internal transcribed spacer sequence was used. Of 55 adult ticks, 22 (40%) were positive for spirochetes as determined by Barbour-Stoenner-Kelly culture passages. In addition, some rodents, including Apodemus uralensis (5 of 14 animals) and Cricetulus longicaudatus (the only animal examined), and some immature stages of I. persulcatus (4 of 11 ticks) that had fed on A. uralensis were positive for spirochetes. Based on 5S-23S rRNA intergenic spacer restriction fragment length polymorphism analysis and reactivity with monoclonal antibodies, 35 cultures (including double isolation cultures) were identified as Borrelia garinii (20 isolates, including 9 Eurasian pattern B isolates and 11 Asian pattern C isolates), Borrelia afzelii (10 pattern D isolates), and mixed cultures (5 cultures, including isolates that produced B. garinii patterns B and C plus B. afzelii pattern D). These findings revealed that Lyme disease pathogens are distributed in the mountainous areas in northwestern China even though it is an arid region, and they also confirmed the specific relationship between I. persulcatus and genetic patterns of Borrelia spp. on the Asian continent.

Animals↗
PubMed2001

Chronic hypernatremia derived from hypothalamic dysfunction: impaired secretion of arginine vasopressin and enhanced renal water handling.

We analyzed the disorder of water metabolism in a 32 year-old female with chronic hypernatremia. She had meningitis at 4 years, and ventriculo-peritoneal shunt operation at 13 years because of normal pressure hydrocephalus. At 14 years hypernatremia of 166 mmol/l was initially found and thereafter hypernatremia ranging from 150 to 166 mmol/l has been persisted for the last 18 years. Physical and laboratory findings did not show dehydration. Urine volume was 750-1700 ml per day and urinary osmolality (Uosm) 446-984 mmol/kg, suggesting no urinary concentrating defect. Plasma arginine vasopressin (AVP) levels ranged from 0.4 to 1.2 pmol/l despite hyperosmolality of 298 through 343 mmol/kg under ad libitum water drinking. There was no correlation between plasma osmolality (Posm) and plasma AVP levels, but Uosm had a positive correlation with Posm (r=0.545, P < 0.05). Hypertonic saline (500 NaCl) infusion after a water load increased Uosm from 377 to 679 mmol/kg, and plasma AVP from 0.2 to 1.3 pmol/l. There was a positive correlation between Posm and plasma AVP levels in the hypertonic saline test (r=0.612, P<0.05). In contrast, an acute water load (20 ml/kg BW) verified the presence of impaired water excretion, as the percent excretion of the water load was only 8.5% and the minimal Uosm was as high as 710 mmol/kg. Urinary excretion of aquaporin-2 remained low in concert with plasma AVP levels. No abnormality in pituitary-adrenocortical function was found. These results indicate that marked hypernatremia is derived from partial central diabetes insipidus and elevated threshold of thirst, and that enhanced renal water handling may contribute to maintenance of body water in the present subject.

Adult↗
PubMed2001

Inhibitory effects of verapamil and nitroglycerin on contraction and cytosolic Ca2+ levels in cerebrovascular smooth muscle during chronic cerebral vasospasm.

The mechanisms of the inhibitory effects of verapamil and nitroglycerin on vasospasm were investigated by measuring cytosolic Ca2+ level ([Ca2+]i) and muscle tension in 28 normal specimens and 28 spastic vascular specimens of smooth muscle. Experimental vasospasm was produced by the two-hemorrhage method in the canine basilar artery. [Ca2+]i and tension were recorded simultaneously with a fluorimeter using fura-2. High K+ concentration (72.4 mM) and U-46619 (thromboxane A2 analogue, 10(-8) M) were used as stimulants, and the inhibitory effects of verapamil or nitroglycerin on muscle contraction and increased [Ca2+]i were examined. Verapamil inhibited [Ca2+]i and contraction in high K+ concentration-stimulated arteries. Verapamil inhibited [Ca2+]i more strongly than contraction in U-46619-stimulated arteries. There were no significant differences in the effects of verapamil in the control and vasospasm groups. Nitroglycerin inhibited contraction with little effect on [Ca2+]i in high K+ concentration-stimulated arteries in both the control and vasospasm groups. Nitroglycerin inhibited contraction with little effect on [Ca2+]i in U-46619-stimulated arteries and the inhibitory effect was weaker in the vasospasm group than in the control group. The inhibitory effects of verapamil on muscle tension and [Ca2+]i in vasospastic vessels were as strong as those in normal vessels. In contrast, the inhibitory effects of nitroglycerin were reduced in vasospastic vessels. Increased Ca2+ sensitivity in vasospastic vessels may have reduced the inhibitory effects of nitroglycerin.

Animals↗
PubMed2000

In-vitro and in-vivo antibiotic susceptibilities of Lyme disease Borrelia isolated in China.

The antibiotic susceptibilities of seven Borrelia burgdorferi sensu lato isolates from Ixodes persulcatus in China were examined by in-vitro microdilution minimum inhibition concentration (MIC) and macrodilution minimum bactericidal concentration (MBC) methods. All isolates tested were susceptible to amoxicillin, erythromycin, and minocycline. The MICs of these drugs for the Chinese isolates were 0.025-0.1 microg/ml, <0.012-0.05 microg/ml, and <0.012-0.05 microg/ml, respectively. The MBCs were 0.1-0.39 microg/ml, <0.012-0.2 microg/ml, and 0.025-0.39 microg/ml, respectively. The in-vivo antimicrobial susceptibilities of the Chinese Borrelia isolates to two test drugs, amoxicillin and minocycline, were evaluated using ddY mice. Mice were infected by subcutaneous inoculation into the right hind footpad. When infection was confirmed, the mice were treated by subcutaneous injection of the test drugs into the back. Amoxicillin and minocycline, which possessed high in-vitro activities against Lyme disease Borrelia, provided good protection against borreliosis in this animal model. Higher doses of these drugs resulted in elimination of the Lyme disease spirochete from all animals receiving this course of treatment. The 50% curative doses (CD50) of amoxicillin and minocycline were 8.7 mg/kg and 3.1 mg/kg, respectively. This suggested that amoxicillin and minocycline could be useful for the treatment of Chinese Borrelia infection.

Amoxicillin↗
PubMed2000

Magnetically suspended rotary blood pump with radial type combined motor-bearing.

A magnetically suspended centrifugal blood pump is being developed with a combined motor-bearing for long-term ventricular assist systems. The combined motor-bearing actively suspends a rotor in a radial direction to deal with radial force unbalance in the pump and rotates the rotor by using the electric magnetic field. Therefore, the pump has no mechanical parts such as bearings of the motor and has a long lifetime. The developed pump consists of a thin rotor with a semi open-type 6 vane impeller and a stator to suspend and rotate the rotor. The rotor has 4-pole permanent magnets on the circumferential surface. The outer diameter and the thickness of the rotor are 60 mm and 8 mm, respectively. Axial movement and tilt of the rotor are restricted by passive stability based on the thin rotor structure. Radial movements of the rotor, such as levitation in radial direction and rotation, are controlled actively by using electric magnets of the stator. The electric magnet coils to produce levitation and rotation forces are constructed on the periphery stator. The p +/- 2-pole algorithm and the synchronous motor mechanism are adopted to levitate and rotate the rotor. The radial gap between the rotor and the stator is 1 mm. A closed-loop circuit filled with water was connected to the developed pump to examine the basic performance of the pump and the magnetic suspension system. Maximum rotational speed, flow rate, and head were 2,800 rpm, 11 L/min, and 270 mm Hg, respectively. The rotor with the impeller could be suspended completely during the entire pumping process. We conclude the pump with the combined motor-bearing has sufficient performance for the blood pump.

Centrifugation↗
PubMed2000

Computational fluid dynamics analysis of a centrifugal blood pump with washout holes.

The authors studied avoidance of coagulation occurrence using computational fluid dynamics (CFD) analysis from the fluid dynamical point of view. Concerning centrifugal pumps, blood coagulation sometimes occurs at the region behind the impeller where the flow is generally stagnant. Therefore, we conducted a thorough study with the specimen pump with and without washout holes, mocking up the Nikkiso HPM-15. As the result, the model with washout holes indicated that the fluid rotates rapidly at the vicinity of the shaft and generates washout effects near the stationary rear casing. On the other hand, the model without washout holes showed that fluid cannot be quickly shipped out of the area behind the impeller and rotates mildly around the shaft. To clarify the moving relations between the impeller and the fluid, validation studies by comparing the results of CFD analysis and flow visualization experiments are ongoing; thus far, the studies show that CFD results are similar to the results from flow visualization experiments.

Centrifugation↗