Search PubMed⌕ Search

Biomedical subjects

Takashi Sasaki

Publications and source records attributed to Takashi Sasaki.

At least 19 recordsLinked to original sources
PubMed2007

Fast skeletal muscle myosin heavy chain gene cluster of medaka Oryzias latipes enrolled in temperature adaptation.

To disclose mechanisms involved in temperature acclimation of fish muscle, we subjected eurythermal fish of medaka Oryzias latipes to cloning of myosin heavy chain genes (MYHs). We cloned cDNAs encoding fast skeletal muscle myosin heavy chain (MYH) isoforms from cDNA libraries of medaka acclimated to 10 and 30 degrees C and observed that different MYH cDNA clones are expressed in the two temperature-acclimated fish. Subsequently, we isolated several overlapping MYH contigs by shotgun cloning strategy from a medaka genomic library. Contig assembly of the complete medaka MYH (mMYH) locus of 219 kbp revealed a cluster of tandemly arrayed 11 mMYHs, in which eight genes are actually transcribed, with the remaining three being pseudogenes. Expression analysis of the transcribed genes revealed that two genes were each highly expressed in medaka acclimated to 10 and 30 degrees C, whereas comparatively lower expression levels of the three genes were exclusively observed in medaka acclimated to 30 degrees C. cDNAs of the remaining genes were too underrepresented in the libraries to determine the expression levels, and the transcripts could only be obtained by reverse transcription-polymerase chain reaction. Deduced amino acid sequences in the loop 1 and loop 2 regions of mMYHs were highly variable, suggesting that these isoforms were functionally different. The present findings consolidate our knowledge on teleost MYH multigene family and would provide further insight into the mechanisms by which expressions of individual MYH molecules are fine-tuned with environmental temperature fluctuations with further functional analysis of the genes concerned.

Adaptation, Physiological↗
PubMed2006

A case of prolactin deficiency with familial puerperal alactogenesis accompanying impaired ACTH secretion.

We report here the case of a 34-year-old female with puerperal alactogenesis. Her menstrual cycle was regular and breast development normal. She had delivered a healthy boy but could not breast-feed after parturition. Endocrinological studies disclosed that the cause was a prolactin (PRL) deficiency. In addition, she showed accompanying impaired ACTH secretion that was believed to be triggered by encephalitis, although her plasma levels of GH, TSH, LH and FSH remained intact. Pituitary MRI showed no specific findings and anti-pituitary antibody tests were negative. Interestingly, both her mother and grandmother also reported puerperal alactogenesis. The sequences of all five exons of the PRL gene, including promoter region and transcription initiation point, were surveyed in order to examine for certain genetic disorders, but no mutations were identified. Although it cannot be definitively concluded that this PRL deficiency was not a genomic DNA disorder, in our case at least, her PRL gene was normal and, therefore, was not directly responsible for the patient's impaired PRL secretion. This evidence suggests that familial puerperal alactogenesis and PRL deficiency can be induced by other causes such as via disorders of unknown transcription factors or molecules that contribute to translation of PRL gene.

Adrenocorticotropic Hormone↗
PubMed2006

The DNA sequence of medaka chromosome LG22.

We report the genomic DNA sequence of a single chromosome (linkage group 22; LG22) of the small teleost fish medaka (Oryzias latipes) as a first whole chromosome sequence from a non-mammalian vertebrate. The order and orientation of 633 protein-coding genes were deduced from 18,803,338 bp of DNA sequence, providing the opportunity to analyze chromosome evolution of vertebrate genomes by direct comparison with the human genome. The average number of genes in the "conserved gene cluster" (CGC), a strict definition of "synteny" at the sequence basis, between medaka and human was 1.6. These and other data suggest that approximately 38.8% of pair-wise gene relationships would have been broken from their common ancestor in the human and medaka lineages and further imply that approx 20,000 (15,520-23,280) breaks would have occurred from the entire genome of the common ancestor. These breaks were generated mainly by intra-chromosomal shufflings at a specific era in the vertebrate lineage. These precise comparative genomics allowed us to identify the pieces of ancient chromosomes of the common vertebrate ancestor and estimate chromosomal evolution in the vertebrate lineage.

Animals↗
PubMed2006

Endoscopic management of biliary complications after adult living donor liver transplantation.

OBJECTIVES: Biliary complications are one of the important issues to be addressed after liver transplantation. Endoscopic management of biliary complications after deceased donor liver transplantation (DDLT) is widely accepted, but it remains to be established in patients after living donor liver transplantation (LDLT). Endoscopic management in LDLT patients is difficult mainly because of the complexity of duct-to-duct reconstruction. METHODS: A total of 174 adult LDLTs with duct-to-duct reconstruction were performed in our institution. Biliary complications developed in 53 patients (30%). Among these, 18 patients were referred for endoscopic management and were the subjects of the present study. Success rate, early morbidity, and outcome were evaluated in these 18 patients. RESULTS: The type of graft was the right liver in six, left liver in eight, and right lateral sector in four patients. Ten out of 18 patients had one biliary anastomosis and the remaining eight had multiple anastomoses. Six patients had a previous history of surgical or percutaneous intervention for biliary complications after LDLT. Seventeen patients had one or more biliary strictures. Biliary casts were found in nine patients, three of whom had concomitant bile leaks. Strictures were successfully treated with endoscopic balloon dilation in 12 (71%) of the 17 patients (nasobiliary catheter placement in eight and stent placement in four patients). Bile leak was successfully managed in two of three patients. Biliary casts were removed by endoscopic papillary balloon dilation in eight of nine patients. Five patients with failed endoscopic therapy were converted to percutaneous or surgical intervention. Endoscopic-procedure-related cholangitis developed in one patient. During follow-up with median periods of 10 months (range 2-20 months), four of nine patients without stent placement developed biliary strictures, and these were relieved by additional endoscopic management. CONCLUSIONS: Endoscopic approach has the potential to be a first-line therapy for the management of biliary complications after LDLT.

Adult↗
PubMed2006

Recent progress on nanovehicles.

Nanovehicles are a new class of molecular machines consisting of a molecular scale chassis, axles, and wheels, that can roll across solid surfaces with structurally defined directions making them of interest to synthetic chemists, surface scientists, chemical engineers, and the general car enthusiast. In this tutorial review, following a brief introduction to the development of nanomachines, our recent progress on the nanovehicle project is presented including the design, synthesis, and testing of a series of nanocars, nanotrucks, and motorized nanocars.

Journal Article↗
PubMed2006

Cholecystitis after metallic stent placement in patients with malignant distal biliary obstruction.

BACKGROUND & AIMS: Cholecystitis after metallic stent (MS) placement is an issue requiring attention. From our experience, cholecystitis seemed to occur mainly in patients with tumor involvement to the cystic duct orifice. The aim of the present study was to identify risk factors for cholecystitis in patients treated with covered or uncovered MS. METHODS: We analyzed 246 patients who received MS placement (covered MS in 171 and uncovered in 75) between August 1997 and May 2005 for the treatment of unresectable distal malignant biliary obstruction. Causative diseases were as follows: pancreatic cancer in 162, papillary cancer in 10, bile duct cancer in 41, and metastatic nodes in 33 patients. Tumor involvement to orifice of the cystic duct (OCD) was diagnosed based on cholangiography and intraductal ultrasonography. RESULTS: Cholecystitis after MS placement was found in 13 patients (5.3%). There was no significant difference in the incidence of cholecystitis between covered (5.8%) and uncovered (4.0%) MS. By univariate analysis, tumor involvement of the OCD, MS placed above the papilla, and stricture located at midportion were associated significantly with cholecystitis. By multivariate analysis, only tumor involvement of the OCD was a risk factor, with an odds ratio of 47.206 (95% confidence interval, 5.84-381.60). CONCLUSIONS: Cholecystitis after MS placement is associated with tumor involvement to the orifice of the cystic duct, regardless of the type of stent.

Aged↗
PubMed2006

Genomic organization of the sex-determining and adjacent regions of the sex chromosomes of medaka.

Sequencing of the human Y chromosome has uncovered the peculiarities of the genomic organization of a heterogametic sex chromosome of old evolutionary age, and has led to many insights into the evolutionary changes that occurred during its long history. We have studied the genomic organization of the medaka fish Y chromosome, which is one of the youngest heterogametic sex chromosomes on which molecular data are available. The Y specific and adjacent regions were sequenced and compared to the X. The male sex-determining gene, dmrt1bY, appears to be the only functional gene in the Y-specific region. The Y-specific region itself is derived from the duplication of a 43-kb fragment from linkage group 9. All other coduplicated genes except dmrt1bY degenerated. The Y-specific region has accumulated large stretches of repetitive sequences and duplicated pieces of DNA from elsewhere in the genome, thereby growing to 258 kb. Interestingly the non-recombining part of the Y did not spread out considerably from the original duplicated fragment, possibly because of a large sequence duplication bordering the Y-specific fragment. This may have conserved the more ancestral structure of the medaka Y and provides insights into some of the initial processes of Y chromosome evolution.

Animals↗
PubMed2006

Surface-rolling molecules.

Design, syntheses, and testing of new, fullerene-wheeled single molecular nanomachines, namely, nanocars and nanotrucks, are presented. These nanovehicles are composed of three basic components that include spherical fullerene wheels, freely rotating alkynyl axles, and a molecular chassis. The use of spherical wheels based on C60 and freely rotating axles based on alkynes permits directed nanoscale rolling of the molecular structure on gold surfaces. The rolling motion observed by STM resembles the same motion performed by macroscopic entities in which rolling occurs perpendicular to the axles. A new synthesis methodology, in situ ethynylation of fullerenes, was developed for the realization of the fullerene-wheeled molecular machines. Four generations of the fullerene-wheeled structures were developed, and the latest fourth generation nanocar, 3b, along with three-wheeled triangular compounds, 4a and 4b, provided definitive evidence for fullerene-based wheel-like rolling motion, not stick-slip or sliding translation. The studies here underscore the ability to control directionality of motion in molecular-sized nanostructures through precise molecular design and synthesis.

Journal Article↗
PubMed2006

Effective plasmid pX3 transduction in Lactobacillus delbrueckii by bacteriophage LL-H.

High-frequency plasmid transductions in Lactobacillus delbrueckii subsp. lactis and subsp. bulgaricus strains mediated by pac-type bacteriophages were observed and further investigated. The frequency of plasmid transduction by phages LL-H and LL-S attained levels of from 0.10 to about 1 with plasmid p X 3, but only about 2 x 10(-2) with plasmid pJK650. Infection of L. delbrueckii subsp. lactis strain LKT(pX3) or ATCC 15808(pX3) with phage LL-H resulted in intensive concatemerization of plasmid pX3, and most progeny phage particles contained concatemers of plasmid DNA instead of phage LL-H DNA. The synthesis of phage LL-H DNA was depressed. No evident homology or recombination was observed between phage LL-H DNA and plasmid pX3. The unusually high frequency of plasmid pX3 transduction by phage LL-H could be considered to result from specific interaction(s) between a particular phage and plasmid. These interactions may include pX3-mediated blockage of phage LL-H DNA replication and effective use of a particular pac-like site located about 1 kb from BglII in the smaller NdeI-BglII fragment of plasmid pX3. Phage LL-H together with plasmid vector pX3 could be used as effective plasmid transduction tools for genetic engineering of L. delbrueckii subsp. lactis and subsp. bulgaricus strains.

Bacteriophages↗
PubMed2006

DNA sequence and analysis of human chromosome 8.

The International Human Genome Sequencing Consortium (IHGSC) recently completed a sequence of the human genome. As part of this project, we have focused on chromosome 8. Although some chromosomes exhibit extreme characteristics in terms of length, gene content, repeat content and fraction segmentally duplicated, chromosome 8 is distinctly typical in character, being very close to the genome median in each of these aspects. This work describes a finished sequence and gene catalogue for the chromosome, which represents just over 5% of the euchromatic human genome. A unique feature of the chromosome is a vast region of approximately 15 megabases on distal 8p that appears to have a strikingly high mutation rate, which has accelerated in the hominids relative to other sequenced mammals. This fast-evolving region contains a number of genes related to innate immunity and the nervous system, including loci that appear to be under positive selection--these include the major defensin (DEF) gene cluster and MCPH1, a gene that may have contributed to the evolution of expanded brain size in the great apes. The data from chromosome 8 should allow a better understanding of both normal and disease biology and genome evolution.

Animals↗
PubMed2006

[18F]fluorodeoxyglucose positron emission tomography is a useful tool to diagnose the early stage of Takayasu's arteritis and to evaluate the activity of the disease.

Takayasu's arteritis (TA) is a rare disease that can be difficult to diagnose in its early stage. A young woman with a fever and neck pain was thought to have TA, although computed tomographic angiography did not show any specific changes of the arteries. [(18)F]fluorodeoxyglucose positron emission tomography ([(18)F]FDG-PET) was performed to detect the source of the inflammation. Specific accumulation of [(18)F]FDG-6-phosphate in the thoracic aorta and its direct branches was observed, leading to a diagnosis of TA. [(18)F]FDG-PET is therefore considered to be useful for the diagnosis of early-stage TA.

Adolescent↗
PubMed2006

Feasibility of duct-to-duct biliary reconstruction in pediatric living related liver transplantation: report of three cases.

Feasibility of duct-to-duct biliary reconstruction in adult living related liver transplantation (LRLTx) has been recently reported; however, little has been known of its surgical outcome in children. To assess the feasibility and safety of duct-to-duct biliary reconstruction in children, the surgical outcomes of duct-to-duct biliary reconstruction were retrospectively analyzed. The subjects were three children who underwent LRLTx in our hospital each utilizing allografts with a right lobe, a left robe and a lateral segment, respectively. The cause of end-stage liver disease in each of them was fulminant Wilson's disease, fulminant hepatic failure and unresectable hepatoblastoma. Duct-to-duct anastomosis was performed in younger patients and adolescents with interrupted and continuous sutures, respectively. The diameter of bile duct in allografts was from 4 to 6 mm and 12 or 13 stitches were required for anastomosis. Post-operative choledochography from the external tube showed neither stenosis nor leakage and the tube was evacuated within 3 months after LRLTx. No biliary complications were observed with the median follow-up of 28 months. In conclusion, our results show that duct-to-duct biliary reconstructions in pediatric LRLTx seemed to be feasible and safe. Further studies are required to elucidate its real impact on pediatric LRLTx.

Adolescent↗
PubMed2006

Strong immunostimulatory activity of AT-oligodeoxynucleotide requires a six-base loop with a self-stabilized 5'-C...G-3' stem structure.

Lactobacillus gasseri OLL2716 has recently been discovered as a probiotic that suppresses the growth of Helicobacter pylori and reduces gastric mucosal inflammation in humans. This has resulted in the development of a new type of probiotic yoghurt 'LG21' in Japan. In our previous study, we found an immunostimulatory AT5ACL oligodeoxynucleotide (AT-ODN) containing a unique core sequence (5'-ATTTTTAC-3') in L. gasseri JCM1131(T). Interestingly, although the AT-ODN does not contain any CpG sequences, it exerts mitogenic activity in B cells and augments Th-1-type immune responses via Toll-like receptor 9. These findings prompted us to identify strong immunostimulatory non-CpG AT-ODNs that contain the 5'-ATTTTTAC-3' motif in the genomic sequence of L. gasseri OLL2716. We identified 280 kinds of AT-ODNs in the L. gasseri OLL2716 genome. Mitogenicity and NF-kappaB gene reporting assays showed that 13 of the 280 AT-ODNs were strongly immunostimulatory when in the TLR9 transfectant. Of these, AT-ODNs LGAT-145 and LGAT-243 were the most potent. With respect to the induction of Th-1-type cytokines, LGAT-243 had the greatest activity and was more potent than the swine prototype, ODN D25. We further found that a six-base secondary loop structure containing a self-stabilized 5'-C...G-3' stem sequence is important for potent immunostimulatory activity. These results show for the first time that AT-ODNs with a specific loop and stem structure are important factors for immunostimulatory activity. Finally, we found that novel strong immunostimulatory non-CpG AT-ODNs exist in the genome of probiotic lactic acid bacteria.

AT Rich Sequence↗
PubMed2006

[Ventriculoperitoneal shunt malfunction due to pregnancy].

A 27-year-old female was admitted to our department due to gait disturbance and disorientation. Computed tomography (CT) scan revealed symmetrical ventricular dilatation. She was pregnant at 25 weeks of gestation. At the age of 16 years, she had received a ventriculo-peritoneal (VP) shunt for hydrocephalus, induced by a cerebellar medulloblastoma. Neurological examination at the current admission showed that she was disoriented with ataxic gait and convergence nystagmus. Analysis of the cerebrospinal fluid showed normal cell composition. Magnetic resonance images (MRI) and Thalium-single photon emission tomography (CI-SPECT) revealed no recurrence of the tumor. The radio-isotope shunt flow study showed there was no obstruction of the shunt tube or retardation of intraabdominal diffusion. The patient was diagnosed as having shunt malfunction without obstruction of the shunt tube. We performed pumping of a flushing device for the shunt system. As a result her symptom was gradually improved. The follow-up MRI, 20 days after the using, showed complete disappearance of hydrocephalus. She was discharged from our hospital 1 month later. She continued pumping of the flushing device by herself at home. Three months later, she delivered a healthy infant by vaginal labor. She has not need to do pumping after that. And MRI showed no sign of hydrocephalus.

Adult↗
PubMed2005

Entropically driven MHC class I recognition by human inhibitory receptor leukocyte Ig-like receptor B1 (LILRB1/ILT2/CD85j).

The human inhibitory receptor, leukocyte immunoglobulin (Ig)-like receptor B1 (also called Ig-like transcript (ILT) 2, CD85j), is broadly expressed on leukocytes. LILRB1 binds to a wide range of major histocompatibility complex class I molecules (MHCIs) and transduces negative signals that can, for example, prevent killing of MHCI-expressing cells. Here we report the kinetic, thermodynamic, NMR and crystallographic analyses of MHCI recognition by LILRB1. Kinetic studies demonstrated that LILRB1 binds to MHCIs with fast association and dissociation rates, typical of cell-cell recognition receptors. Thermodynamic analyses showed that LILRB1-MHCI interactions are entropically driven (-TdeltaS = -9.4 approximately -6.6 kcal mol(-1)) with low heat capacity changes (deltaC(p) = -0.22 approximately -0.10 kcal mol(-1) K(-1)). The crystal structures of LILRB1 in the different crystal forms exhibited variation in the elbow angle between the two N-terminal Ig-like domains, indicating interdomain flexibility. Consistently, NMR analysis provided the direct evidence of the conformational changes of LILRB1 upon the MHCI binding. These findings suggest that LILRB1-MHCI interactions, while involving some conformational adjustment, are not accompanied by a very large reduction in conformational flexibility at the binding interface. This mode of binding is distinct from "induced-fit" binding, which is associated with large reductions in conformational flexibility, and would be suitable for rapid engagement of MHCIs to enable fast monitoring of the expression level of MHCIs on target cells.

Antigens, CD↗
PubMed2005

Recurrent acute pancreatitis caused by malrotation of the intestine and effective treatment with laparoscopic Ladd's procedure.

We herein report a rare case of recurrent pancreatitis caused by malrotation of the intestine. Since the age of 10 years, a female patient showed recurrent epigastralgia and was diagnosed at age 16 years as suffering from acute pancreatitis. Upper gastrointestinal series showed that the duodenal bulb was elongated and rotated caudally. Endoscopic retrograde cholangiopancreatography showed that the descending portion of the duodenum was rotated and occluded the papilla of Vater. Under laparoscopy, the duodenal bulb was tracted caudally by the Ladd's ligament. By incision of this ligament, the entire duodenum was mobilized, with subsequent reduction of the rotation and compression of the pancreatic head. The girl's postoperative course was uneventful, and she has been asymptomatic for the last 3 years. In conclusion, malrotation of the intestine may be a rare cause of recurrent pancreatitis, and laparoscopic Ladd's procedure may be a less invasive and useful treatment.

Acute Disease↗
PubMed2005

Synthesis, spectroscopic and nonlinear optical properties of multiple [60]fullerene-oligo(p-phenylene ethynylene) hybrids.

A series of multiple [60]fullerene terminated oligo(p-phenylene ethynylene) (OPE) hybrid compounds has been synthesized through a newly developed in situ ethynylation method. Structural and magnetic shielding properties of the highly unsaturated carbon-rich C(60) and OPE scaffolds were characterized by 1D and 2D NMR spectroscopic analyses. Electronic interactions between the [60]fullerenes and the OPE backbones were investigated by UV/Vis spectroscopic and cyclic voltammetry (CV) experiments. Our studies clearly show that although the multiple [60]fullerene groups are connected via pi-conjugated OPE frameworks, they present diminutive electronic interactions in the ground state, and the electronic behavior of the [60]fullerene cages are only affected by the OPE backbones through modest inductive effects. Interestingly, sizable third-order nonlinear optical (NLO) responses (gamma) and enhanced two-photon absorption (TPA) cross-sections (sigma((2))) were determined for the multifullerene-OPE hybrid 31 relative to its OPE precursor from differential optical Kerr effect (DOKE) experiments. Such enhanced NLO performance is presumably due to the occurrence of periconjugation and/or charge transfer effects in the excited state. In addition, comparatively strong excited-state absorption was observed and characterized for OPE pentamer 12. Thus, the use of such fullerene-derivatized conjugated oligomers aids the quest for molecules with large third-order NLO and TPA properties.

Fullerenes↗