Biomedical subjects

T Tomonaga

Publications and source records attributed to T Tomonaga.

At least 19 recordsLinked to original sources

PubMed2007

Chromosome instability and kinetochore dysfunction.

Chromosomal instability (CIN) has been recognized as a hallmark of human cancer and is caused by continuous chromosome missegregation during mitosis. Proper chromosome segregation requires a physical connection between spindle microtubules and centromeric DNA and this attachment occurs at proteinaceous structures called kinetochore. Thus, defect in kinetochore function is a candidate source for CIN and the generation of aneuploidy. Recently, a number of kinetochore components have been shown to be mutated and/or aberrantly expressed in human cancers, which suggests an important role of kinetochore for CIN and carcinogenesis. In this article, we will discuss about how kinetochore dysfunction causes CIN and might lead to the development of cancer.

Chromosomal Instability↗

PubMed2004

Establishment of a clonal human mesenchymal cell line that retains multilineage differentiation capacity from a spinal hamartoma.

We isolated a single-cell-derived cell line from a spinal hamartoma, a which occurred in a newborn boy and was associated with a rudimentary limb. The maternal cells (HHC-7) differentiated into osteoblasts, chondrocytes, adipocytes, and skeletal muscles when they were cultured in differentiation-inducing media specific to each mesenchymal cell. We isolated a single-cell-derived clonal cell line (Clone K) after transfection with SV40 T antigen. These cells expressed CD73 and CD117, while being negative for expression of CD45. Clone K cells cultured in an osteogenic differentiation medium increased ALP activity and expressed mRNAs for Runx2 and osteocalcin. Treatment with rhBMP-2 induced Clone K cells to differentiate into both osteoblasts and chondrocytes. These cells expressed mRNAs for Sox9 and aggrecan in addition to osteogenic markers. Culture in an adipogenic differentiation medium induced Clone K cells to differentiation into adipocytes, which expressed mRNAs for PPARgamma2 and a2P. Clone K cells cultured in a serum-depleted medium generated desmin-positive cells and expressed MyoD1 mRNA. Clone K cells exhibited numerous alpha-smooth muscle actin-positive cells; however, treatment with rhBMP-2 decreased their number. Clone K cells, transplanted with a carrier containing rhBMP-2 into the muscles of SCID mice, generated ectopic endochondral bone formation. In these tissues, several osteoblasts and chondrocytes expressed SV40 T antigen, indicating their Clone K cell origin. Thus, Clone K cells are useful tools for analyzing the characteristics of human multipotential mesenchymal progenitors.

Adipocytes↗

PubMed2004

Vascular-pedicled costal cartilage graft for the treatment of subglottic and upper tracheal stenosis.

BACKGROUND/PURPOSE: Free costal cartilage graft for the treatment of subglottic and tracheal stenosis is widely used, but postoperative granulation formation is a problem. To reduce the risk of granulation formation after free costal graft, a new operation of costal cartilage graft with vascular pedicle was introduced. METHODS: A vascular pedicled fifth costal cartilage graft is prepared using internal thoracic artery and vein and intercostal artery and vein as a vascular pedicle. The prepared graft is brought to the upper trachea. The anterior wall of cricoid is split, and the costal cartilage graft is implanted to the split part and tracheostomy. Extubation on the next day is possible if the general condition of the patient permits. RESULTS: In 3 cases of subglottic or upper tracheal stenosis, this operation was performed. All the patients had tracheostomy made during early infancy. The postoperative course was uneventful, and all the patients were extubated soon after the operation. No granulation tissue was observed by postoperative bronchoscopic examinations. CONCLUSIONS: Costal cartilage graft with vascular pedicle is a safe and useful new operation for the treatment of subglottic and upper tracheal stenosis. There also is a possibility of using this procedure for the treatment of long segment tracheal stenosis.

Cartilage↗

PubMed2004

Inhibition of subgenomic hepatitis C virus RNA in Huh-7 cells: ribavirin induces mutagenesis in HCV RNA.

Hepatitis C virus (HCV) infection is a major problem throughout the world. Combination therapy of interferon (IFN) and ribavirin is the best treatment for eradication at present, but the mechanism is not completely understood. We used the HCV replicon system to investigate this mechanism. The effects of six drugs (UDCA, glycyrrhizin, TJ-9, bezafibrate, ribavirin, and alpha-IFN 2b) on HCV subgenomic RNA (genotype 1b, NS5B 415Y) were examined by reverse transcription polymerase chain reaction, cloning and sequencing. The HCV replication was inhibited by alpha-IFN 2b (7.39-13.2% at 10 U/mL, 3.29-6.12% at 100 U/mL, 1.3-4.86% at 1000 U/mL) and by ribavirin (4.36-13.9% at 100 microg/mL), but not by the other drugs at 24-72 h after treatment. Furthermore, the combination treatment was superior to IFN monotherapy and to ribavirin monotherapy at 72 h post-treatment. Sequence analyses of the double-stranded RNA-activated protein kinase (PKR)-binding domain and flanking regions within the HCV NS5A region revealed that the total numbers of substitutions caused by ribavirin (n = 36) or combination treatment (n = 57) were more than those of IFN alone (n = 5) and controls (n = 6). The HCV replicon system is the most efficient system for HCV replication and is an excellent choice for testing anti-HCV drugs and disinfectants. Our results further suggested that the combination of alpha-IFN 2b and ribavirin might induce mutations, and inhibit HCV RNA synthesis in hepatocytes to a greater extent than ribavirin monotherapy.

Amino Acid Substitution↗

PubMed2000

Characterization of fission yeast cohesin: essential anaphase proteolysis of Rad21 phosphorylated in the S phase.

Cohesin complex acts in the formation and maintenance of sister chromatid cohesion during and after S phase. Budding yeast Scc1p/Mcd1p, an essential subunit, is cleaved and dissociates from chromosomes in anaphase, leading to sister chromatid separation. Most cohesin in higher eukaryotes, in contrast, is dissociated from chromosomes well before anaphase. The universal role of cohesin during anaphase thus remains to be determined. We report here initial characterization of four putative cohesin subunits, Psm1, Psm3, Rad21, and Psc3, in fission yeast. They are essential for sister chromatid cohesion. Immunoprecipitation demonstrates stable complex formation of Rad21 with Psm1 and Psm3 but not with Psc3. Chromatin immunoprecipitation shows that cohesin subunits are enriched in broad centromere regions and that the level of centromere-associated Rad21 did not change from metaphase to anaphase, very different from budding yeast. In contrast, Rad21 containing similar cleavage sites to those of Scc1p/Mcd1p is cleaved specifically in anaphase. This cleavage is essential, although the amount of cleaved product is very small (<5%). Mis4, another sister chromatid cohesion protein, plays an essential role for loading Rad21 on chromatin. A simple model is presented to explain the specific behavior of fission yeast cohesin and why only a tiny fraction of Rad21 is sufficient to be cleaved for normal anaphase.

Anaphase↗

PubMed2000

Left side thoracoscopically assisted gastroplasty: a new technique for managing the shortened esophagus.

Laparoscopic antireflux surgery is the procedure of choice for gastroesophageal reflux disease (GERD). However, many clinicians have reservations about its application in patients with complicated GERD, notably those with esophageal shortening. In this report, we present our experience with the laparoscopic management of the shortened esophagus. A total of 235 patients with primary GERD underwent laparoscopic antireflux procedures, 38 of whom were suspected preoperatively to have a shortened esophagus. Of the 235 patients, 8 (3.4%) needed a left thoracoscopically assisted gastroplasty in addition to laparoscopic Toupet repair (n = 4) or Nissen fundoplication (n = 4). Complications included pleural effusion (n = 1), pneumothorax (n = 2), and minor atelectasis (n = 1). The average hospital stay was 3 days. Results were satisfactory in 7 of 8 patients, with a mean follow-up of 20.2 months (range, 9-34 months). The surgical management of the shortened esophagus is difficult. However, the role of minimally invasive techniques is justified. Early results are appealing, with less morbidity, satisfactory control of GERD related symptoms, and a shortened hospital stay.

Esophagus↗

PubMed2000

Persistent dysphagia after laparoscopic vagotomy.

BACKGROUND: Laparoscopic vagotomy represents a new and less invasive treatment for peptic ulcer disease, but the problem of postvagotomy dysphagia has not been solved. The aim of this study was to determine the etiologic factors related to long-term laparoscopic postvagotomy dysphagia. METHODS: Two female and 11 male patients with a mean age of 48.5 years who underwent laparoscopic vagotomy were investigated retrospectively. Preoperative diagnosis included duodenal ulcer resistant to medical treatment, gastric hypersecretion, gastric outlet obstruction, cholelithiasis, and gastroesophageal reflux disease (GERD). Ten patients underwent laparoscopic highly selective vagotomy, and three patients had laparoscopic truncal vagotomy with gastrojejunostomy or pyloroplasty. Nine of these patients had a Nissen fundoplication in conjunction with the vagotomy. RESULTS: The median long-term follow-up period was 47 months. Two patients complained of severe dysphagia, one of moderate dysphagia, and two of mild dysphagia. Neither type of vagotomy nor an additional fundoplication was correlated with the severity of postoperative long-term dysphagia. Severity of postoperative dysphagia was associated with severity of preoperative dysphagia (r = 0.752, p = 0.003) but not with heartburn (r = 0.358, p = 0.531) or regurgitation (r = 0.024, p = 0.938). The cause of preoperative dysphagia varied; however, all of these patients had GERD and consequent esophageal lesions. CONCLUSION: Preexisting dysphagia appears to play an integral role in persistent postoperative dysphagia. Care must be taken to construct a loose fundoplication in patients with dysphagia.

Cholelithiasis↗

PubMed2000

Does the duration of gastroesophageal reflux disease and degree of acid reflux correlate with esophageal function? A retrospective analysis of 768 patients.

To reconfirm that the duration of symptoms is not associated with esophageal motility in patients with gastroesophageal reflux disease (GERD), esophageal manometric data from 768 patients with GERD were retrospectively analyzed with relation to the duration of symptoms. GERD was defined by positive acid reflux test results monitored by ambulatory 24-hour pH monitoring. Correlation of the duration of symptoms with esophageal body pressures, the presence of dysmotility determined by simultaneous waves, average resting pressure of the lower esophageal sphincter (LES), and abdominal and overall lengths of the LES were statistically analyzed. The median duration of the symptoms was 60 months (range, 1-600). Duration of symptoms was not associated with contraction pressures of the esophageal body at 3 and 8 cm above the LES (r = -0.070 and -0.063, respectively). There was no correlation between LES pressures, LES lengths, or the percentage of simultaneous waves and duration of symptoms. Stricture formation is related to decreased distal esophageal function in GERD patients. In conclusion, the duration of GERD has little influence on esophageal body and LES function.

Adolescent↗

PubMed1999

Fission yeast condensin complex: essential roles of non-SMC subunits for condensation and Cdc2 phosphorylation of Cut3/SMC4.

The condensin complex in frog extracts, containing two SMC (structural maintenance of chromosomes) and three non-SMC subunits, promotes mitotic chromosome condensation, and its supercoiling activity increases during mitosis by Cdc2 phosphorylation. Here, we report that fission yeast has the same five-member condensin complex, each of which is essential for mitotic condensation. The condensin complex was purified and the subunits were identified by microsequencing. Cnd1, Cnd2, and Cnd3, three non-SMC subunits showing a high degree of sequence conservation to frog subunits, are essential for viability, and their gene disruption leads to a phenotype indistinguishable from that observed in cut3-477 and cut14-208, known mutations in SMC4 and SMC2-like subunits. Condensin subunits tagged with GFP were observed to alter dramatically their localization during the cell cycle, enriched in the nucleus during mitosis, but cytoplasmic during other stages. This stage-specific alteration in localization requires mitosis-specific phosphorylation of the T19 Cdc2 site in Cut3. The T19 site is phosphorylated in vitro by Cdc2 kinase and shows the maximal phosphorylation in metaphase in vivo. Its alanine substitution mutant fails to suppress the temperature-sensitive phenotype of cut3-477, and shows deficiency in condensation, probably because Cut3 T19A remains cytoplasmic. Therefore, direct Cdc2 phosphorylation of fission yeast condensin may facilitate its nuclear accumulation during mitosis.

Amino Acid Sequence↗

PubMed1999

Endo-organ full-thickness excision for gastric cancer: report of a case.

We performed endo-organ full thickness gastric excision to treat a high-risk patient with T2 gastric cancer. The patient, a 75-year-old white man with a gastric adenocarcinoma located just below the gastroesophageal junction, had a history of chronic obstructive pulmonary disease and cor pulmonale, and developed markedly elevated pulmonary artery pressures under general anesthesia. The less invasive endo-organ approach was utilized because of these severe morbidities. The carcinoma was staged laparoscopically, then removed utilizing the full-thickness endo-organ excision technique. This case report serves to demonstrate that full thickness endo-organ gastric excision may be indicated not only for certain early gastric cancers, but also for high-risk patients who cannot tolerate open surgery due to advanced age or serious illness.

Adenocarcinoma↗

PubMed1999

Laparoscopic intracorporeal ultrasound cystic duct length measurement: a new technique to prevent common bile duct injuries.

The incidence of common bile duct injury remains high. Intracorporeal ultrasound mapping of cystic duct anatomy, prior to laparoscopic cholecystectomy (LC), may assist surgeons in avoiding common bile duct injuries. A technique for intraoperative intracorporeal predissection ultrasound imaging (IIPUI) of the cystic duct length was tested. During LC, gallbladder adhesions were lysed, and with the gallbladder retracted by grasping forceps, the ultrasound examination was performed. Using a 7.5-MHz articulating ultrasound probe, visualization of the extrahepatic biliary tree was obtained in five separate planes. Success in visualizing each plane, time for ultrasound examination, and predissection accuracy of cystic duct length measurement were recorded. Intraoperative cholangiography or direct measurement of the dissected cystic duct was used to determine accuracy of the ultrasound cystic duct length estimates. Forty-three patients underwent IIPUI during LC. The time required to perform the examination varied, with a range of 5 to 17 min (mean 9.5 min). Success of visualization in planes 1 through 5 was 44%, 95%, 98%, 98%, and 70%, respectively. The accuracy rate for cystic duct length ultrasound measurement was 87.1%. No complications related to the examination were observed. In this preliminary study, cystic duct length was determined by predissection intracorporeal ultrasound with a high level of accuracy. Predissection imaging may assist in preventing common bile duct injury during LC.

Adult↗

PubMed1999

A combined laparoscopic-endoscopic method of assessment to prevent the complications of short esophagus.

As antireflux surgery has been used increasingly for gastroesophageal reflux disease (GERD), a need has arisen for an accurate method to assess esophageal length. There are a number of preoperative tests that can help surgeons to establish the presence of a short esophagus, but intraoperative assessment after esophageal mobilization is the standard method. In this era of laparoscopic surgery, the surgeon mobilizes the esophagus extensively from the abdomen and then determines if mobilization is sufficient. We report an intraoperative technique that combines laparoscopic with endoscopic methods to determine the position of the gastroesophageal junction. Because two physicians are required, there is additional operating room time, resulting in increased costs. However, these costs are offset by the assurance that the complications of the short esophagus can be avoided. With experience, modifications were made, resulting in the technique described herein.

Endoscopy↗

PubMed1999

A new form of access for endo-organ surgery. The initial experience with percutaneous endoscopic gastrostomy.

BACKGROUND: Intraluminal gastric surgery provides a new treatment option for various disease processes. This study assesses the safety of a new large-diameter percutaneous endoscopic gastrostomy (PEG) for intraluminal surgery. METHODS: Investigators at six institutions were asked to complete a standard questionnaire to assess the difficulties associated with the assembly and introduction of the PEG, plus intraoperative and postoperative problems related to placement of the device. RESULTS: In terms of assembly; 1.9% of respondents reported difficulty obtaining complete vacuum of the balloon tip, and 3.8% had difficulty fitting the graduated dilator to the balloon-tipped cannula. Difficulties associated with introduction of the PEG included disengagement of the dilator from the balloon-tipped cannula (0%), extraction of the dilator-port assembly (0%), difficult PEG pullout (1.9%), abdominal wall bleeding (0%), and difficult PEG dilator separation (7.5%). Intraoperatively, 7.5% of respondents reported inadequate skin bolster fitting, 1.9% had CO(2) leakage into the peritoneal cavity, 0% had inadvertent PEG extraction, and 0% reported injury to the esophagus, colon, or small intestine. Postoperatively, there was a 9.4% rate of wound infection, a 1.9% rate of gastrocutaneous fistula, and a 1.9% rate of esophageal, colon, or small intestine injury. CONCLUSIONS: The large-diameter PEG is safe and effective for endo-organ surgery. Additional preventive measures for PEG site infection should be investigated.

Adult↗

PubMed1999

Manometric and radiographic verification of esophageal body decompensation for patients with achalasia.

BACKGROUND: Although morphologic, radiographic, and manometric features of achalasia have been well defined, it has not been established by careful retrospective analysis whether achalasia is a progressive disorder resulting in complete decompensation. STUDY DESIGN: To verify the hypothesis that achalasia is a progressive disease, we retrospectively investigated manometric, radiographic, and symptomatic data in patients with achalasia. Sixty-three patients (36 women and 27 men) with a median age of 44 years (range 11 to 79 years) were evaluated. The duration of symptoms ranged from 1 to 442 months, with a median of 48 months. Patients were divided into four groups according to the duration of symptoms: 36 patients with less than 5 years, 11 with 5 to 10 years, 9 with 10 to 15 years, and 7 with 15 years or more. RESULTS: Contraction pressures of the esophageal body decreased significantly at every level when the duration of symptoms increased (p < 0.04). The percentage of simultaneous waves in the esophageal body rose as the duration of symptoms increased. All waves were synchronous in every patient who had had symptoms for more than 15 years. The maximal width of the esophageal body measured on esophagram became greater with an increase in the duration of symptoms, but this measurement did not reach statistical significance (p = 0.063). The tortuosity of the esophagus, measured by the maximal angle of the esophageal axis, was significantly greater in patients with a longer duration of symptoms (p < 0.02). The type of symptoms was not associated with the duration of symptoms. CONCLUSIONS: Achalasia is a progressive disease, as verified by manometric and radiographic findings. The classification of esophageal motor function expressed by amplitude of contraction pressure and angle of tortuosity is objective and useful. Classification of achalasia by duration of symptoms may be important in treatment selection and effectiveness.

Adolescent↗

PubMed1999

Screening for yeasts incorporating the exogenous eicosapentaenoic and docosahexaenoic acids from crude fish oil.

The screening for yeasts incorporating exogenous eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) into their cellular lipids was conducted. Two percent of oil from fish scraps was added to a yeast isolation medium as a sole carbon source. From 143 soil samples, we isolated 23 yeast strains, nine of them were found to be capable of quickly assimilating the scrap fish oil. These nine strains, in addition to four previously isolated triglyceride-assimilating and lipase-producing strains, Yarrowia lipolytica and three Geotrichum species (FO274A, FO347-2 and FO401B), were cultured in a growth medium at 30 degrees C. Strains FO726A, FO765A and FO347-2 were selected on the basis of dry cell weight production and ability to store EPA and DHA in their cells, and their performance was further compared by varying cultivation temperature and time. From 1 g of the scrap fish oil, FO726A yielded 620 mg of dry cells, containing 47.1% lipid, 38.1% triglyceride, 3.3% EPA, and 4.9% DHA, when cultured at 25 degrees C for 36 h. Strain FO726A apparently has the highest ability to incorporate EPA and DHA into its cellular lipids. Results from further experiments showed that the incorporated EPA and DHA mainly existed in the form of triglyceride in the FO726A cell. These results suggest that FO726A is suitable for the production of cell mass rich in EPA and DHA for feed.

Journal Article↗

PubMed1998

An unusual case of endometrial trocar site implantation.

We present the case of a 35-year-old woman with a history of apparent bilateral hernia who had a surgical intervention that included a diagnostic laparoscopy converted to open laparotomy. The patient experienced endometrial implants exclusively at trocar sites. This case is cited as validation of the pneumoperitoneum-induced free cell implantation theory, or the so-called aerosolization theory.

Abdomen, Acute↗

PubMed1998

Unrestraining genetic processes with a protein-DNA hinge.

Genetic processes require direct interactions between proteins bound at nonadjacent cis elements. Because duplex DNA is rigid, either the protein-protein interactions are strong enough to deform the double helix or some feature of the intervening DNA must encourage juxtaposition of separated sites. For example, bent DNA can bring together only certain precisely positioned cis elements with the same helical phase. Interposing a DNA segment that both bends and twists easily to create a universal joint would provide an even more general mechanism to promote the association of separated sites regardless of position. A cis element of the human c-myc gene, known to be melted in vivo, and its associated single-strand DNA binding protein were examined and found to comprise just such a protein-DNA hinge.

DNA, Single-Stranded↗

PubMed1997

Clinical, radiographic, and kinematic results from an adjustable four-pad halovest.

STUDY DESIGN: Charts and radiographs of all patients treated with this halovest at one university hospital were reviewed retrospectively. OBJECTIVES: To describe the outcomes from an adjustable four-pad halovest and to compare them with those from standard halovests, as previously published. SUMMARY OF BACKGROUND DATA: With standard halovests, there can be cervical motion up to 70% of normal values, substantial loads between the halo and vest, and complications of pin loosening, pin infections, and scapular pressure sores. The four-pad vest reduces halovest loads and vest-torso motions. METHODS: The four-pad vest has four independently adjustable pads that completely avoid contact with the scapula, clavicle, and abdomen. Clinical records were analyzed to determine the incidences of halo pin loosening, pressure sores, injury or surgical site nonunion, and loss of cervical alignment. Lateral radiographs were taken with the patient in the upright and supine positions at various times to determine intervertebral rotations (flexion-extension). RESULTS: The clinical results with the four-pad vest were at least as good as those for standard vests. Scapular pressure sores were prevented completely by the absence of vest-scapula contact. Kyphosis did not increase significantly with time. The mean segmental rotations were all 3 degrees or less and showed a smoothly decreasing pattern from C1-C2 to C6-C7. The value at Oc-C1 was opposite to that at C1-C2 and is the subject of further analysis. CONCLUSIONS: The rotations occurring with the four-pad vest are less than or equal to those occurring with standard vests, for overall cervical rotation and for individual motion segment rotations. This is consistent with the smaller halovest forces seen with this vest. Prospective, comparative testing will assess the clinical significance of these findings.

Adult↗