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Biomedical subjects

M Takagi

Publications and source records attributed to M Takagi.

At least 109 records · Page 6Linked to original sources
PubMed2001

Isomerization of DNA-bound distilbazolium ligand induced by electron transfer from photoexcited tris(1,10-phenanthroline)Ru(II).

The ability of the DNA duplex to behave as an efficient organized medium for cis-trans isomerization induced by electron transfer (ET) has been explored. Isomerization studies, luminescence quenching and DNA photocleavage assays show that photoexcited Ru(1,10-phenanthroline [phen])3(2+) transfers an electron to E,Z1,4-bis[2-(1-methylpyridinium-4-yl)vinyl]benzene (E,Z pMPVB), which subsequently undergoes one-way isomerization to E,E pMPVB. The unusual feature of the system is manifested by the lack of friction that is usually imposed on the photoisomerizable ligand by highly organized media. The apparent rate of ET in DNA increases when compared with the homogeneous solution. However, after correction for the local concentration of the reagents onto the biopolymer, the rate constant becomes independent of the DNA concentration and is at least 4 x 10(2) times smaller than that in the homogeneous aqueous solution. Using the photoinduced isomerization system, a large enhancement in the efficiency of single-strand break formation was found in plasmid DNA over that for Ru(phen)3(+2) alone using irradiation at lambda > 480 nm.

DNA↗
PubMed2001

Movement of Aedes aegypti (Diptera: Culicidae) released in a small isolated village on Hainan Island, China.

A mark-release-recapture experiment was conducted in a small isolated village on Hainan Island, China, to examine the dispersal and movement of adult Aedes aegypti (L.). Two cohorts of mosquitoes marked with uniquely colored fluorescent dye were released at two different sites and recaptured for 6 d at every house in the village using human bait collections. The distribution pattern of houses around release site affected dispersal. The recapture rate of females released at the center of the village was higher (3.49%) than females released at the edge of the village (2.47%). The average day of recapture differed significantly between sexes, but not cohorts. The average day of recapture of females and males released at the center was 2.5 and 1.54 d, respectively. The total number of mosquitoes recaptured was the greatest at premises near the release site, and decreased at a constant rate of 0.43-0.48 with increasing distance from the release site. The proportion of nulliparous females decreased during the first 4 d and proportion of females with developing or mature ovaries increased during the latter half of the experiment. The daily survival rate for females and males released at the center of the village was estimated by log-regression to be 0.763 and 0.52, respectively.

Aedes↗
PubMed2001

An inferior mesenteric-caval shunt via the internal iliac vein with portosystemic encephalopathy.

We report here a case of an unusual extrahepatic portosystemic venous shunt in a 37-year-old woman without liver cirrhosis or portal hypertension, who developed portal systemic encephalopathy. Angiography demonstrated an inferior mesenteric-caval shunt characterized by the presence of direct communication of the inferior mesenteric vein with the left internal iliac vein. After the treatment with percutaneous transcatheter embolization of the shunt via a femoral vein approach using coils, she had no episode of portal systemic encephalopathy.

Adult↗
PubMed2001

Gene expression and immunohistochemical localization of decorin and biglycan in association with early bone formation in the developing mandible.

We investigated the expression of the small proteoglycans, decorin and biglycan, which are associated with osteoblast differentiation, and how this relates to the expression of osteocalcin and bone sialoprotein (BSP) early in the formation of bone in the rat mandible by immunohistochemistry and in situ hybridization. The mandibles of rat fetuses were collected on embryonic days 14 (E14) to E18. In situ hybridization showed that gene expression of decorin, biglycan, osteocalcin and BSP was not apparent in the developing mandible at E 14, but was expressed by newly differentiated osteoblasts at E15. The expression of these mRNAs increased linearly as the number of osteoblasts increased in specimens from E16 to E18. Immunohistochemistry showed that newly differentiated osteoblasts expressed biglycan moderately, decorin weakly, and osteocalcin and BSP faintly. The unmineralized bone matrices among the osteoblasts showed prominent staining for decorin, weak staining for osteocalcin and BSP, and very weak staining for biglycan. When the intercellular matrix was mineralized at E16, the mineralized bone matrix showed more prominent staining for osteocalcin and BSP, but lacked staining for decorin and biglycan. The same staining profile was observed during the subsequent phases of bone formation at E17 and E18. These results indicate that decorin, biglycan, osteocalcin and BSP are expressed at the gene and protein level by newly differentiated osteoblasts before the onset of matrix mineralization and that they could play a role in the earliest stages of bone formation. Negative proteoglycan staining in the mineralized bone matrix suggests that a loss of, or a sharp decrease in proteoglycans occurs concomitant with bone matrix mineralization.

Animals↗
PubMed2001

Multifocal electroretinograms in patients with branch retinal artery occlusion.

PURPOSE: To investigate the usefulness of second-order multifocal electroretinograms (MERGs) for detecting inner retinal disorders. METHODS: The MERG from 5 patients with branch retinal artery occlusion (BRAO) was recorded. Twelve eyes of 12 normal subjects were also tested. MERGs were recorded using 61 hexagons. Bright flash ERGs were also recorded to measure the oscillatory potentials (OP). Root mean square (RMS) measures of the local first- and second-order MERGs (fMERG and sMERG) were compared in the affected and unaffected areas. The first negative trough (N1) and first positive peak (P1) were also used for measuring the amplitudes and latencies of the fMERG. RESULTS: The fMERG RMS-amplitudes decreased significantly (r = 0.56, P: < 0.05) in the affected area compared with normal values. The fMERG latencies of N1 and P1 increased significantly (P: < 0.05) in the affected area. Furthermore, the sMERG RMS-amplitudes decreased almost to the noise level (r = 0.28, P: < 0.001) in the affected areas. The interocular ratio of the sMERG RMS-amplitudes (affected/normal) significantly correlated with that of the fMERG (r = 0.69, P: < 0.001). The fMERG latencies significantly correlated with the sMERG RMS-amplitude (r = 0.37 approximately 0.69, P: < 0.05 approximately 0.001), but only began to increase after a 30% to 50% loss of the sMERG amplitude. The summed OP amplitude decreased to the same extent as the sMERG in the affected eye (0.5 of the normal eye). CONCLUSIONS: Although the fMERG amplitude and latency were significantly changed, the sMERG was much more affected by BRAO. The marked reduction of the sMERG in the affected area strongly suggested its main source was from the more inner layers of the retina compared to the fMERG. The sMERG appeared to be a sensitive indicator of inner retinal dysfunction.

Adolescent↗
PubMed2001

Cross-axis adaptation of pursuit initiation in humans.

PURPOSE: The initial acceleration of pursuit in the open-loop period is under adaptive control and undergoes motor learning. The current study was undertaken to examine the hypothesis that the direction of pursuit initiation can also be adaptively modified. METHODS: Four neurologically and ophthalmologically normal subjects participated in the experiment. A modified step-ramp paradigm was used to induce cross-axis adaptation, in which a ramp target changed its direction orthogonally just after the target crossed the center. Four direction changes were tested in separate experiments: left to up, left to down, down to left, and up to left. During a 30-minute adaptation session, the target moved in one of two randomly chosen directions (right to left or up to down) at one of two randomly chosen speeds (15.6 or 22.3 deg/sec), but the target changed orthogonally in only one direction. A linear regression fit to the initial 100-msec segment of the pursuit trace was used to determine the direction of pursuit initiation. RESULTS: In all cases, an adaptive change in pursuit initiation was gradually induced in the direction called for by the training paradigm. Adaptation was usually completed (90 degrees shift) within the 30-minute training session but declined quickly to an approximate 30 degrees -shift after training. The latency and vectorial amplitude of the initial acceleration remained unchanged. The adaptation was specific for the direction but not the velocity of the target. CONCLUSIONS: This study showed that the direction of pursuit initiation is under adaptive control, as has been shown for saccadic eye movements and the vestibulo-ocular reflex.

Adaptation, Ocular↗
PubMed2001

Impaired final follicular maturation in heifers after superovulation with recombinant human FSH.

The aim of this study was to investigate whether human FSH without contaminating LH can exert a normal superovulation response in cows. One group of heifers (n = 9) was stimulated with recombinant human FSH (rhFSH), an FSH source without any LH activity, and another group (n = 9) was treated with equine chorionic gonadotrophin (eCG), an FSH source with high LH activity. Daily transrectal ultrasonography showed that eCG- and rhFSH-stimulated heifers (n = 9 per group) had the same follicular growth characteristics and equal numbers of follicles > 8 mm in diameter after 3 days of stimulation. The treatment groups differed considerably in steroid production: rhFSH-treated heifers produced much lower oestradiol concentrations than did eCG-stimulated heifers during the first days of stimulation and much lower progesterone concentrations in the period after the LH surge. During the 27-35 h after prostaglandin injection, rhFSH-treated heifers had fewer LH pulses than did eCG-treated heifers (0.3 versus 3.0 per heifer, respectively; n = 3 per group). All rhFSH-treated heifers (n = 6) underwent a preovulatory LH surge, but this occurred significantly later than in the eCG-treated heifers (n = 4; 39.4 +/- 1.9 h versus 47.1 +/- 1.5 h in rhFSH- and eCG-treated heifers, respectively). Multiple ovulations occurred in only three of six rhFSH-treated heifers, but in all four eCG-treated heifers with an LH surge. At 24 h after the LH surge, the percentage of metaphase II stage oocytes with cortical granules distributed close to the oolemma was significantly lower in the rhFSH group (7.3%) than in the eCG group (55.9%). In conclusion, final follicular maturation is impaired in heifers treated with rhFSH, which might be due to the combination of a lack of LH activity in the gonadotrophin preparation and the severe suppression of LH pulsatility.

Animals↗
PubMed2001

Adaptive changes in dynamic properties of human disparity-induced vergence.

PURPOSE: Vergence eye movements undergo adaptive recalibration in response to a training stimulus in which the initial disparity is changed just after vergence begins (the double-step paradigm). In the present study the changes in the dynamic properties of convergence, speed and acceleration, were examined by using this double-step paradigm, before and after adaptation. METHODS: Four normal subjects participated. Three-dimensional visual stimuli were provided by a head-mounted display with two liquid crystal diode (LCD) panels. To induce adaptation, a double step of disparity was used: an initial step from distances of 2 to 1 m was followed by a second step to distances of 0.7 m ("increasing paradigm") or 1.4 m ("decreasing paradigm") after a constant period of 0.2 seconds. The dynamic properties of vergence were compared before and after 30 minutes of training with these paradigms. RESULTS: Peak velocity of convergence became significantly greater (increasing paradigm) or smaller (decreasing paradigm) after 30 minutes' training. Changes in the dynamic properties of convergence were also obvious in phase-plane (velocity versus position) and main sequence (peak velocity versus amplitude) plots. Further analysis revealed that adaptive increases in vergence velocity were accomplished by an increase in the duration of the acceleration period, whereas adaptive decreases were induced by a decrease in the maximum value of acceleration. CONCLUSIONS: The pattern of change in the dynamic characteristics of vergence after adaptation was similar to that of saccades and the initiation of pursuit eye movements, suggesting common neural mechanisms for adaptive changes in the open-loop control of eye movements.

Adaptation, Ocular↗
PubMed2001

Evidence for a new sibling species of Anopheles minimus from the Ryukyu Archipelago, Japan.

The Anopheles minimus complex is known to comprise at least 2 sibling species (A and C) in Thailand and Vietnam. This study investigated the specific status of An. minimus on Ishigaki Island, the Ryukyu Archipelago, Japan using morphological and genetic analyses. Morphological studies revealed that almost all (99.5%) of the adult mosquitoes are characterized by the humeral pale spot on the costa of their wings, a character that partially differentiates species A and C elsewhere. A high frequency (81.4%) have a pale fringe spot at the tip of vein 1A, a character rarely observed in other An. minimus populations. Significant seasonal variation in the size of wild An. minimus mosquitoes on the island was observed, with the largest size in the winter. Scanning micrographs of the cibarial armature of females from Ishigaki Island revealed that over 90% had cone filaments clearly differing in shape from those of species A or C. The Giemsa-stained metaphase karyotypes of larval brain cells were somewhat similar to those of species A, with a few exceptions, but were very different from those reported for species C. Crossing experiments between species A (CM strain) from Thailand and the progeny of An. minimus from Ishigaki Island (ISG strain) revealed postzygotic genetic incompatibility, although no prezygotic isolation. Hybrid progeny were only obtained from CM female x ISG male. F2 hybrid progeny were not obtained, since the hybrid males were sterile or almost sterile with atrophied testes or abnormal spermatozoa, although the polytene chromosomes of hybrid larvae showed synapsis. The hybrid females backcrossed with either CM or ISG males laid eggs with significantly lowered fertility and viability. The sequence for the D3 region of the 28S gene of ribosomal DNA of the ISG strain differed from those of species A and C. In addition, sequence data from Vietnamese mosquitoes suggest that the An. minimus complex may contain additional species. The morphological, cytogenetic, molecular, and hybridization evidence together suggest the existence of another sibling species of the An. minimus complex on Ishigaki Island, which is provisionally designated An. minimus species E.

Animals↗
PubMed2001

[A case with upper limb dominant Guillain-Barré syndrome and serum IgG anti-GT1a antibodies: sparing oropharyngeal palsy].

We report a 78-year-old man with Guillain-Barré syndrome (GBS) who showed upper limb dominant muscle weakness following an upper respiratory infection. He had no weakness in extraocular, oropharyngeal and neck muscles. Tendon reflexes were absent in his upper limbs. Electrophysiological studies suggested demyelination of motor nerves in his upper and lower extremities. He had serum IgG antibodies to GM1 and GT1a but not to GQ1b. Anti-GT1a antibodies did not cross-react to GM1 by means of the absorption test. Titers of the antibodies decreased after recovering from muscle weakness of upper limbs. Since the presence of serum antibodies to GT1a but not to GQ1b were reported in patients with pharyngeal-cervical-brachial weakness of Guillain-Barré syndrome, it has been suggested that anti-GT1a antibodies play a role in acute oropharyngeal neuropathy. This is the first report of a patient with GBS lacking oropharyngeal palsy who had serum IgG antibodies to GT1a but not to GQ1b. Our case suggests that anti-GT1a antibodies are related not only with acute oropharyngeal neuropathy but also with upper limb dominant motor neuropathy.

Aged↗
PubMed2001

P53 and MDM2 co-expression in tobacco and betel chewing-associated oral squamous cell carcinomas.

Oral cancers of tobacco and betel chewers represents a unique in-vivo model to understand the genotoxic effect of tobacco and betel carcinogens on oncogenes and tumor suppressor genes. Coordinated interactions of p53 and MDM2 play an important role in regulation of critical growth control gene following exposure to DNA damaging agents. The purpose of this study is to determine if the tumor suppressor function of p53 is inactivated by mutation or other alternative mechanisms in carcinogen-induced oral squamous cell carcinoma (SCC), and to investigate the clinicopathological significance of p53 and MDM2 expression. The p53 mutation in oral SCC of tobacco and betel chewers (n=40) was detected by polymerase chain reaction - single strand conformation polymorphism (PCR-SSCP) analysis and immunohistochemistry (IHC) was done to investigate p53 and MDM2 proteins overexpression. The incidence of p53 mutation was relatively low (17.5%), but there was a high prevalence of MDM2 overexpression (72.5%). In the total of 40 cases, IHC phenotype showed p53 positive immunostaining with MDM2 positive immunostaining (p53+/MDM2+) 62.5%, p53 negative immunostaining with MDM2 negative immunostaining (p53-/MDM2-) 15%, p53 positive immunostaining with MDM2 negative immunostaining (p53+/MDM2-) 12.5%, and p53 negative immunostaining with MDM2 positive immunostaining (p53-/MDM2+) 10%. A significant correlation was found between MDM2 and p53 overexpression (p=0.0289). Moreover, p53+/MDM2+ phenotype was significantly associated with poorly differentiated tumors (p= 0.0007). These results conclude that other factors than p53 mutation is likely to be the targets of tobacco/betel carcinogens and MDM2 may play an important role in tobacco/betel chewing-related oral SCCs. Overexpression of MDM2 protein may constitute an alternative mechanism for p53 inactivation.

Areca↗
PubMed2000

Messenger ribonucleic acid expression of 16 matrix metalloproteinases in bone-implant interface tissues of loose artificial hip joints.

Matrix metalloproteinases (MMPs) have been reported to be the major factors responsible for aseptic loosening of artificial hip joints. So far, messenger ribonucleic acid (mRNA) expression patterns of seven MMPs have been reported, but that of many other MMPs which have been newly discovered or recently considered to be responsible for prosthetic loosening is still unknown. In this study, mRNA expression pattern of 16 different types of MMPs were analyzed to evaluate which MMPs were locally produced and contributed to prosthetic loosening. Synovium-like interface tissues between bone and prosthesis were collected from 18 cases of aseptic loose artificial hip joint at revision surgery. Six cases of normal synovium were used as controls. Total RNA was extracted by single-step acid guanidinium-thiocyanate-phenol-chloroform procedure. mRNA expression of MMPs was analyzed by semiquantitative reverse transcription-polymerase chain reaction. Based on local expression pattern of MMPs at the mRNA level, aseptic loose artificial hip joint was characterized by elevated expression of MMP-1, MMP-9, MMP-10, MMP-12, and MMP-13; moderate expression of MMP-2, MMP-7, MMP-8, MMP-11, membrane type (MT)1-MMP (MMP-14), MT2-MMP (MMP-15), MT3-MMP (MMP-16), MT4-MMP (MMP-17), and MMP-19; lower expression of MMP-3; and little significance of MMP-20. The MMPs detected in this study can potentially degrade almost all components of the periprosthetic extracellular matrix. Thus, many MMP type enzymes possibly contribute to prosthetic loosening and osteolysis through pathologic extracellular matrix degradation and connective tissue/bone remodeling around prostheses.

Aged↗
PubMed2000

Crystal structure of the haloalkane dehalogenase from Sphingomonas paucimobilis UT26.

The haloalkane dehalogenase from Sphingomonas paucimobilis UT26 (LinB) is the enzyme involved in the degradation of the important environmental pollutant gamma-hexachlorocyclohexane. The enzyme hydrolyzes a broad range of halogenated cyclic and aliphatic compounds. Here, we present the 1.58 A crystal structure of LinB and the 2.0 A structure of LinB with 1,3-propanediol, a product of debromination of 1,3-dibromopropane, in the active site of the enzyme. The enzyme belongs to the alpha/beta hydrolase family and contains a catalytic triad (Asp108, His272, and Glu132) in the lipase-like topological arrangement previously proposed from mutagenesis experiments. The LinB structure was compared with the structures of haloalkane dehalogenase from Xanthobacter autotrophicus GJ10 and from Rhodococcus sp. and the structural features involved in the adaptation toward xenobiotic substrates were identified. The arrangement and composition of the alpha-helices in the cap domain results in the differences in the size and shape of the active-site cavity and the entrance tunnel. This is the major determinant of the substrate specificity of this haloalkane dehalogenase.

Binding Sites↗
PubMed2000

Quantitative Evaluation of Nystagmus by an Image-analysis System.

Purpose: We attempted to apply a newly developed image-analysis system for measurement and analysis of nystagmus.Method: Eye movements were recorded by digital video through a head-mounted charge coupled device (CCD) camera. The recorded movie was converted into black and white in order to detect the area of the pupil. Horizontal and vertical eye positions were determined by calculating the centroid of the pupil. Torsional angle was calculated using the iris striate pattern around the pupillary margin.Results: The parameters (amplitude, cycle, etc.) of nystagmus were calculated easily by the new image-analysis system from the recorded images. As examples, the foveation period was measured accurately in a case of jerky-type congenital nystagmus. Very regular cycles of intorsional attack period were revealed in a case of superior oblique myokymia. A case of cork-screw-like nystagmus showed a characteristic combination of large and small cycles unassociated with torsion.Conclusion: This image-analysis system was useful for quantitative analysis of nystagmus, and especially for measurement of torsion. Detailed waveforms and specific rhythms of nystagmus, which could not be recognized by observation, were demonstrated by this system.

Journal Article↗
PubMed2000

Expression of the bph genes involved in biphenyl/PCB degradation in Pseudomonas sp. KKS102 induced by the biphenyl degradation intermediate, 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid.

The bph genes involved in PCB/biphenyl degradation in Pseudomonas sp. KKS102 are clustered as bphEGFA1A2A3BCDA4R. The bph genes are inducibly expressed in the presence of biphenyl. In order to understand the induction more fully, the inducer of bph gene expression was investigated. To identify the inducer molecule, we constructed four deletion mutants of the structural genes and analyzed the inducibility of the bphE gene in each mutant strain. In the wild-type cell and the bphD deletion mutant, the levels of the bphE transcript were enhanced in the presence of biphenyl. On the other hand, in the bphA, bphB, and bphC deletion mutants, levels of the bphE transcript were not enhanced in the presence of biphenyl. These results demonstrated that the series of reactions catalyzed by biphenyl dioxygenase (BphA), dihydrodiol dehydrogenase (BphB), and 2, 3-dihydroxybiphenyl dioxygenase (BphC) are necessary to convert biphenyl to the inducer. It is known that these reactions convert biphenyl to 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid (HOPDA), and it was found that the expression of the bph genes was induced by purified HOPDA. These results clearly indicate that HOPDA is the inducer of the bph genes in KKS102.

Biodegradation, Environmental↗
PubMed2000

The cytochrome P450ALK multigene family of an n-alkane-assimilating yeast, Yarrowia lipolytica: cloning and characterization of genes coding for new CYP52 family members.

Genes encoding cytochromes P450 of the CYP52 family in the n-alkane-assimilating yeast Yarrowia lipolytica have been cloned and analyzed. Degenerate PCR primers which were designed for the conserved amino acid sequences of cytochromes P450ALK of Candida species were used for amplification and isolation of genes encoding P450ALK from a genomic DNA library of Y. lipolytica CX161-1B. Seven new genes (YlALK2-YlALK8) were isolated. Five of the seven YlALK genes were induced by n-alkane under the culture conditions used in this study, whereas their expression was strictly repressed by glycerol but not by glucose, similar to the case of YlALK1, reported previously. Disruption of YlALK2, YlALK3, YlALK4 or YlALK6 did not change the growth of Y. lipolytica on medium containing n-alkanes of various chain lengths. A mutant with disruptions in both YlALK1 and YlALK2 did not grow well on n-hexadecane, whereas one with disruptions in both YlALK1 and YlALK3, which has the same phenotype as the YlALK1 singly disrupted mutant, grew well on n-hexadecane. These results suggest that the presence of multiple P450ALK species is a rather common phenomenon among the n-alkane-assimilating yeasts and that in the n-alkane assimilation of Y. lipolytica, YlALK1 functions to assimilate n-decane and longer molecules, whereas YlALK2 is involved in the assimilation of molecules longer than n-dodecane; other YlALKs are not significantly involved in the assimilation of C10-C16 n-alkanes.

Alkanes↗
PubMed2000

The forkhead-associated domain of Ki-67 antigen interacts with the novel kinesin-like protein Hklp2.

The Ki-67 antigen (pKi-67) is widely used as a cell proliferation marker protein. Its actual role in the cell cycle progression, however, is presently unclear. Using a two-hybrid screening in yeast, a novel protein, termed Hklp2 (human kinesin-like protein 2), was identified and shown to interact with the forkhead-associated (FHA) domain of pKi-67. Hklp2 has 1388 amino acids and shows a striking similarity (a 53% identity in amino acids) to Xklp2, a plus-end directed kinesin-like motor found in Xenopus. The interaction domain of Hklp2 was mapped to the portion that comprised residues 1017-1237 and that was phosphorylated in vitro by incubating with mitotic but not interphasic HeLa cell extracts. That the interaction was striking in the mitotic extract was also verified. In addition, immunofluorescence using specific antibodies revealed an association between pKi-67 and Hklp2 at the periphery of mitotic chromosomes, largely in close proximity to the centromeres. These findings suggest that pKi-67 is involved in the progression of mitosis via its interaction with Hklp2.

Amino Acid Sequence↗