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Biomedical subjects

Yuichi Murayama

Publications and source records attributed to Yuichi Murayama.

At least 19 recordsLinked to original sources
PubMed2006

Efficient in vitro amplification of a mouse-adapted scrapie prion protein.

Protein misfolding cyclic amplification (PMCA) is a highly sensitive technique used to detect minute amounts of scrapie prion protein (PrP(Sc)), a major protein component of the infectious agents associated with prion diseases. Although exponential in vitro amplification of hamster scrapie PrP(Sc) has been established, the PMCA used was unsuccessful in achieving good amplification of PrP(Sc) from other animals. Here, we have investigated the cause of the insufficient PrP(Sc) amplification in mice and have developed an improved method suitable for amplification of the PrP(Sc) of the mouse-adapted scrapie prion strain Chandler. Mouse PrP(C), the cellular form of the prion protein, tends to become resistant to proteases during incubation independent of sonication. By adding digitonin to the reaction buffer as a lipid detergent, accumulation of the protease-resistant PrP(C) was inhibited; hence, mouse PrP(Sc) could be amplified to infinite levels. The present study is the first report describing effective amplification of PrP(Sc) of the mouse-adapted scrapie prion and this improved PMCA technique will contribute to prion research that uses mice as experimental animals.

Animals↗
PubMed2006

Comparative analysis of estrogen receptor gene polymorphisms in apes.

Polymorphic microsatellite repeats in the promoter region of estrogen receptor alpha gene (ESRalpha and the intron 6 region of estrogen receptor beta gene (ESRbeta) have been reported in human populations. To examine the evolutional state of both repeats, we surveyed the corresponding regions in DNA sequences from the following great apes and gibbons: 56 chimpanzees, 3 bonobos, 16 gorillas, 20 orangutans and 60 gibbons (four species: 17 of Hylobates agilis, 11 of H. lar, 15 of H. muelleri, and 17 of H. syndactylus). In the corresponding region of the TA repeat of human ESRalpha, chimpanzees and bonobos had two motifs in the repeat tract, (TA)(7-9) and (CA)(4-6). Gorillas had the (TA)(9-10) repeat tracts and orangutans had monomorphic (TA)(7) repeats. Although all great apes maintained the TA expansion, all gibbon sequences contained (TA)(2), implying that the CA dinucleotide expansion arose in the ancestor of chimpanzees and bonobos. The nucleotide sequences of ESRbeta showed a very complex repeat pattern in apes. The human sequences had a non-variable preceding sequence at (CA)(n), (GA)(2)(TA)(8)(CA)(4)(TA). In apes that region included {(TA)(n)(CA)(n)}(n). Gibbon sequences included (TATG)(n) and (TATC)(n) and no regular construction was observed. A deletion event in the reverse primer site seems to have occurred in the orangutan lineage. In addition, a great diversity of allele length was detected in each gibbon species.

Animals↗
PubMed2006

Divergence of ape and human monoamine oxidase A gene promoters: comparative analysis of polymorphisms, tandem repeat structures and transcriptional activities on reporter gene expression.

A variable number of tandem repeats (VNTR) polymorphism based on a 30-bp unit have been reported in the promoter region of the human monoamine oxidase A gene (MAOA). Human VNTRs have been shown to affect transcriptional activity, and some reports suggest that VNTR polymorphisms are associated with psychoneurological disorders. VNTR polymorphism has also been reported in the ape MAOA promoter but the transcriptional activities of the alleles remain to be determined. In the present study, we sequenced the 1.3-kb promoter region of ape MAOA and compared the transcriptional activities of ape MAOA promoter sequences with those of humans. All apes examined were polymorphic in the region corresponding to the human VNTR and two, four, three, and two alleles were found in chimpanzees, gorillas, orangutans, and gibbons, respectively. VNTR repeat structures in gorillas, orangutans, and gibbons were considerably different from those in humans and chimpanzees. In a human neuroblastoma cell line, most of the ape sequences that had a short repeat length (12bp or 18bp) exhibited higher promoter activity than a human 3-repeat sequence with a 30-bp repeat length. However, an intra-species difference dependent on the repeat number was not observed among the ape alleles examined.

Animals↗
PubMed2006

Protein misfolding cyclic amplification as a rapid test for assessment of prion inactivation.

Abnormal isoform of prion proteins (PrP(Sc)), which are infectious agents associated with prion diseases, retain infectivity after undergoing routine sterilization processes. A sensitive method to detect the infectivity is a bioassay, and it has been used for assessing prion inactivation. However, the result is obtained after several hundred days. Here, protein misfolding cyclic amplification (PMCA) in which PrP(Sc) can be amplified in vitro was applied for assessing prion inactivation by dry heating and autoclaving. Scrapie-infected hamster brains were inactivated under various conditions, and residual infectivity and PrP(Sc) were detected by the bioassay and PMCA, respectively. The PMCA results were in good agreement with those of the bioassay. In samples autoclaved at temperatures below 150 degrees C, while infected mice died in the bioassay, protease-resistant PrP (PrP(res)) signals were detected in the second or third round of PMCA. Three rounds of PMCA require only 6 days, which means that the PMCA method is much faster than the bioassay.

Animals↗
PubMed2006

Comparison of androgen receptor CAG and GGN repeat length polymorphism in humans and apes.

Two polymorphic trinucleotide repeats of human androgen receptor gene (hAR), CAG and GGN which encode glutamine and glycine, have been shown to be associated with human diseases. The number of repeats ranges from 8 to 35 for the CAG and from 10 to 30 for the GGN in human populations. Longer CAG repeats are associated with reduced hAR transcriptional activity, spinal bulbar muscular atrophy and lower cognitive function in older men, whereas shorter CAG repeats are associated with increased risk of prostate cancer and infertility in men. The functional roles of the CAG and GGN repeats have not been clarified. In order to compare the sequence of the CAG and GGN regions in apes, we analyzed 57 chimpanzees, 18 gorillas, 20 orangutans, 16 agile gibbons, and 17 siamangs by PCR and electrophoresis. Two bonobos and one long-tailed macaque were also sequenced and the sequences of all species were aligned, respectively, with one human registered sequence. Seventeen different alleles (4, 7, 8, 9, 12, 14, 15, and 17-26 repeats) and 11 alleles (11-14 and 16-22 repeats) were detected at the CAG and the GGN loci, respectively. Although the repeat tract was conserved among apes, chimpanzees had alleles with a wide range of repeat lengths: (CAG)(14-26) and (GGN)(14-22). Gorillas were less polymorphic with the (CAG)(8) and (GGN)(19) alleles being most common, and orangutans exhibited monomorphic (CAG)(11) and (GGN)(22) alleles. On the other hand, agile gibbons and siamangs had the shortest (CAG)(4) allele, but showed variable length of GGN repeats (11-13 in agile gibbons and 16-21 in siamangs). In chimpanzees, frequent haplotypes consisting of short CAG repeats and long GGN repeats or vice versa was observed as in humans.

Animals↗
PubMed2006

Challenges in the endovascular treatment of giant intracranial aneurysms.

OBJECTIVE: Giant intracranial aneurysms present unique therapeutic intricacies. The purpose of this study was to evaluate the anatomic and hemodynamic characteristics of these lesions and the current endovascular and combined surgical and endovascular techniques available for their treatment. METHODS: A review of the literature and the personal experiences of the authors with endovascular treatment of giant aneurysms are presented. This review included anatomic and hemodynamic features and analysis of the diverse endovascular techniques that have been reported for the management of these aneurysms. RESULTS: Anatomic features that create particular challenges in the therapeutic approach of giant aneurysms include size, shape (saccular, fusiform, serpentine), neck dimensions, branch involvement, intraluminal thrombosis, and location. Hemodynamic characteristics that affect endovascular treatment are lateral or terminal aneurysm type of flow and embolic material placement (inflow versus outflow aneurysmal region). The current endovascular therapeutic approaches include parent artery occlusion, trapping, endosaccular embolization with or without adjunctive techniques such as balloon-assisted or stent placement, and combined surgical and endovascular approaches, mainly with surgical revascularization and endovascular occlusion. CONCLUSION: Although there are a wide variety of endovascular therapeutic options for the treatment of giant intracranial aneurysms, none of the current techniques is completely successful and free of complications in the management of these complex lesions. A detailed and individualized analysis of each case in conjunction with sufficient understanding of the anatomy and hemodynamics of a particular aneurysm should guide the therapeutic decision. Further research advances will assist in elucidating the factors predisposing to genesis, progression, and aggressive clinical manifestations of these giant lesions.

Blood Vessel Prosthesis↗
PubMed2006

Endovascular operating suite: future directions for treating neurovascular disease.

OBJECT: The purpose of this study was to evaluate initial experiences in a surgical operating room (OR) with a multipurpose angiography unit, which offers integrated neurosurgical and radiological capabilities. METHODS: A specially designed biplane digital subtraction (DS) angiography system was installed in the neurosurgery OR. The new suite, which allows three-dimensional DS angiography with C-arm for computerized tomography and microsurgery capabilities, allows the neurosurgeon to perform a wide range of neurosurgical and endovascular procedures. Three hundred thirty-two procedures were performed in the endovascular OR between November 2003 and March 2005. Patients arriving in the emergency department were transferred to the endovascular OR without delay. The neurovascular team performed diagnostic angiography followed by endovascular interventional procedures or surgery. CONCLUSIONS: The newly designed endovascular OR facilitates safe and systemic treatment of neurovascular disease.

Aged↗
PubMed2006

Initial clinical experience with matrix detachable coils for the treatment of intracranial aneurysms.

OBJECT: The Matrix detachable coil is a new bioactive, bioabsorbable coil used in the endovascular embolization of intracranial aneurysms. It has a platinum core covered with a bioactive, bioabsorbable polymer (polyglycolic acid/lactide). The authors report on their initial midterm clinical experience with the first-generation Matrix detachable coil. METHODS: One hundred twelve patients harboring 118 aneurysms were treated using Matrix coils. Forty-nine aneurysms (41.5%) were associated with acute subarachnoid hemorrhage (SAH). Twenty-four lesions (49%) were harbored by patients with Hunt and Hess Grade I, 11 (23.4%) by patients with Grade II, eight (16.3%) by those with Grade III, and six (12.2%) by those with Grade IV. Four aneurysms (3.4%) were harbored by patients who had presented with nonacute SAH. Sixty-five aneurysms (55%) were unruptured. Fifty-seven lesions (48.3%) were small with a small neck, 29 (24.6%) were small with a wide neck, 30 (25.4%) were large, and two (1.7%) were giant. All patients were followed up to obtain angiography and clinical outcome data. Technical complications occurred in six patients: two thromboembolic complications and four aneurysm perforations. Of these six patients, the status of two deteriorated because of aneurysm perforation and another two because of thrombus formation (morbidity 3.6%). There were five deaths--one due to rerupture after embolization. Angiography follow-up studies of 87 aneurysms were obtained. Seventy aneurysms demonstrated progressive occlusion or a stable neck (80.5%), and 17 had some degree of recanalization (19.5%). The aneurysms originally diagnosed as a neck remnant showed a 15% rate of recanalization. CONCLUSIONS: Matrix coils can be delivered into aneurysms with technical complications similar to those encountered using GDCs. Midterm anatomical outcomes to date have shown moderate improvement in the recanalization rate when compared with those realized using the GDC system. Because of the increased friction associated with the first-generation Matrix coil, the packing density in most aneurysms was less than that achieved with GDCs. Prolonged angiography follow-up evaluations are needed to document long-term efficacy.

Absorbable Implants↗
PubMed2006

[Endovascular treatment of large petrous internal carotid artery aneurysm associated with chronic otitis media: case report].

Aneurysms of the petrous internal carotid artery are rare, and surgical treatment of the aneurysm in the petrous bone carries high risk with procedure. We report a case of large petrous internal carotid artery aneurysm associated with otitis media. A 58-year-old female was admitted to our institution with left hearing loss and facial palsy. She had 4-year history of left exudative otitis media. Imaging studies demonstrated a 17 mm left petrous internal carotid artery aneurysm, destroying osseous partition between carotid canal and Eustachian tube, and protruding into left middle cranial fossa. Endosaccular coil embolization with balloon assist technique was performed successfully without neurological deficit. Follow up magnetic resonance angiogram demonstrated complete obliteration of the aneurysm without parent artery occlusion. Traumatic, mycotic, radiation, and congenital origin have been implicated for petrous internal carotid artery aneurysm. In a review of the literature, 11 cases of mycotic aneurysms in this location were reported and all of them were complicated with chronic otitis media. Because of its close proximity of middle ear and Eustachian tube, adventitial infection of the artery weakens the arterial wall, and gives rise to formation of aneurysm. We conclude that our case is of mycotic origin, and endosaccular coil embolization is effective and less invasive treatment.

Aneurysm↗
PubMed2006

[A case of recurrent gastric cancer effectively treated by combined chemotherapy of weekly paclitaxel (PTX) and CDDP].

The patient was a 63-year-old man who underwent distal gastrectomy for advanced gastric cancer with lymph node metastasis and peritoneal dissemination. One year and eleven months after the operation,an increasing CA 19-9 concentration and metastases to the liver and peritoneum were observed. Oral TS-1 was given, but had to be discontinued because of anorexia and nausea. Chemotherapy consisting of paclitaxel (PTX) and CDDP was performed. PTX (80 mg/body) was administered weekly on day 1, 8 and 15, while CDDP (50 mg/body) was administered weekly on day 1 as one cycle. After two cycles of PTX/CDDP administration,metastases to the liver and peritoneum were not detected. The patient was treated with five courses of PTX/CDDP and survived without recurrence as of this writing. PTX/CDDP was associated with few adverse events in hospital visits, and thought to be an effective chemotherapy against recurrent gastric cancer.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2005

Healing of intracranial aneurysms with bioactive coils.

Inadequate healing is an important mechanism for aneurysm development and recanalization after embolization. Matrix coils have been shown by experimental studies to enhance vascular repair and fibrosis, thus reducing the risk of recanalization. The clinical application of Matrix coils represents the transition from pure mechanical occlusion to adjunct biologic healing of aneurysms. Our preliminary clinical experience reveals evidence of a healing response in aneurysms treated with Matrix coils. This technology can be further improved through the incorporation of new knowledge on the molecular pathogenesis of aneurysms and the cellular and molecular mechanisms of healing.

Absorbable Implants↗
PubMed2005

Development of medical devices for neuro-interventional procedures: special focus on aneurysm treatment.

Since the introduction of the Guglielmi detachable coil in 1990, the role of endovascular treatment for intracranial aneurysm has changed significantly. However, this endovascular modality has intrinsic technical limitations in wide-neck and large (11-25 mm) or giant (>25 mm) aneurysms. Long-term anatomic outcomes for these aneurysms include an approximate 25% recanalization rate. Since the aneurysm recanalization is related to morphologic, hemodynamic and biologic factors associated with aneurysm healing, improvement of these factors has elicited several technical modifications of the original technique. This review will describe new endovascular devices that have been manufactured to improve the technical limitations inherited by the Guglielmi detachable coil technique, as well as the historic background of endovascular treatment for cerebral aneurysms.

Blood Vessel Prosthesis↗
PubMed2005

Endovascular management of dissecting vertebrobasilar artery aneurysms in patients presenting with acute subarachnoid hemorrhage.

OBJECT: The authors report on a series of 29 patients presenting with acute subarachnoid hemorrhage (SAH) related to the rupture of a vertebrobasilar dissecting aneurysm. Special attention was focused on embolization techniques and immediate and midterm anatomical and clinical outcomes. METHODS: Between March 1994 and January 2003, 29 patients presented with acute SAH caused by the rupture of a vertebrobasilar dissecting aneurysm. Eleven patients (37.9%) had Hunt and Hess Grade I SAH, four (13.8%) Grade II, six (20.7%) Grade III, five (17.2%) Grade IV, and three (10.3%) Grade V. Aneurysms were classified into five groups based on lesion location, and treatment courses were decided. All patients except two were treated by endovascular trapping of the aneurysm with concomitant occlusion of the involved vertebral artery (VA). No technical or clinical complication was observed in 28 patients (97%). Aneurysm perforation occurred during the procedure in one patient (3%). There was evidence of aneurysm recanalization in one patient. One patient with Hunt and Hess Grade IV SAH and two patients with Grade V SAH died. One patient died of respiratory infection 1 year after aneurysm trapping. One patient presented with a recurrent hemorrhage 1 month after treatment and died. Overall morbidity and mortality rates were 13.8 and 17.2%, respectively. CONCLUSIONS: Twenty-nine patients with acute SAH due to rupturing of vertebrobasilar dissecting aneurysms were treated using endovascular techniques. In most cases, endovascular trapping of the aneurysm and concomitant occlusion of the VA was technically and clinically successful.

Aneurysm, Ruptured↗
PubMed2005

Angiographic evidence of aneurysm neck healing following endovascular treatment with bioactive coils.

A new angiographic finding in intracranial aneurysms embolized with Matrix coils is described. Two illustrative cases with a well-defined radiolucent separation between the coil mass and the parent artery are presented. To the best of our knowledge, this is the first report in humans of this finding. On the basis of prior histopathologic studies, this finding, which we call the "white-collar sign," may indicate the formation of a thick connective tissue barrier between aneurysm and artery that prevents any further aneurysmal filling.

Adolescent↗
PubMed2004

Polymorphism in the second intron of dopamine receptor D4 gene in humans and apes.

The dopamine receptor D4 (DRD4) has received increasing research attention in behavioral science, psychiatry, and psychopharmacology. However, the number of available genetic markers for primates is still insufficient. We identified a novel variation/polymorphism in the second intron of DRD4 in humans based on the survey of 210 Japanese: a 6bp insertion (allele frequency: 0.002) and 8bp deletion (0.024); however, 94 Hungarian Caucasians were found to be monomorphic. Polymorphisms of the homologous region were also found in a survey of 93 specimens from four species of great apes and 51 specimens from seven species of gibbons. The polymorphisms consist of both single nucleotide substitutions and variations in the number of tandem duplications of short GC-rich sequences. Because of usefulness of primates in behavioral science, this polymorphism may be a useful marker for association studies with behavioral traits in both humans and apes.

Animals↗
PubMed2004

Allele frequency distribution of the canine dopamine receptor D4 gene exon III and I in 23 breeds.

Various canine breeds are remarkably different from each other not only in their sizes and shapes but also in behavioral traits, suggesting that some of them are under genetic control. Although dopaminergic neurotransmission system is considered to affect animal behavior, little is known about related genes in canine. Relations between specific alleles in polymorphic regions of the dopamine receptor D4 gene (DRD4) and personality or psychiatric disorders have been reported in humans, and we first found polymorphism in exon III region of the gene in 4 canine breeds. In this study we surveyed allele frequency distribution in 23 breeds including a total of 1,535 unrelated individuals. In exon III, 8 alleles including a novel allele were identified. A group of breeds in which the alleles 447b, 498 and 549 were frequent tended toward high scores in aggression-related behavioral traits than that with frequent alleles 435 and 447a. Moreover, a polymorphism based on 24 bp insertion/deletion was found in exon I region for the first time in dogs. This information may be of use for candidate gene studies of behavioral variation in dogs.

Amino Acid Sequence↗