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Biomedical subjects

T Tada

Publications and source records attributed to T Tada.

At least 19 recordsLinked to original sources
PubMed2004

Comparison of duodenal stent placement with surgical gastrojejunostomy for palliation in patients with duodenal obstructions caused by pancreaticobiliary malignancies.

BACKGROUND AND STUDY AIMS: Palliative treatment for duodenal stenosis with an enteral stent is effective in enhancing the quality of life of patients with duodenal obstruction. There have been no thorough comparisons of duodenal stent placement with standard surgical gastrojejunostomy. The present study evaluated the outcome of duodenal stent placement and surgical gastrojejunostomy for palliation of duodenal stenosis caused by pancreaticobiliary malignancies. PATIENTS AND METHODS: Medical records for patients who underwent palliative enteral stenting during the past 9 years were retrospectively reviewed, and the patients' clinical outcome was compared with that in patients who underwent open surgical gastrojejunostomy during the same period. Patients who underwent prophylactic gastrojejunostomy were excluded from the study. RESULTS: Twenty patients (11 men, nine women; mean age 71.8 years) with pancreaticobiliary malignancy underwent palliative enteral stenting (stent group). Nineteen patients (12 men, seven women; mean age 68.7 years) with pancreaticobiliary malignancies underwent surgical gastrojejunostomy (bypass group). In the stent group, the diagnoses were 12 pancreatic cancers, six gallbladder cancers, one bile duct cancer, and one ampullary cancer. In the bypass group, the diagnoses were 14 pancreatic cancers and five gallbladder cancers. There were no significant differences between the two groups with regard to clinical background. Both procedures were successful. There were no differences between the two groups with regard to the technical or clinical success rates, patient survival, possibility of discharge, need for parenteral nutrition, or incidence of complications. However, the time from the procedure to resumption of food intake was shorter in the stent group than in the bypass group (1 day vs. 9 days; P < 0.0001). Improvement in the performance score after the procedure was observed more frequently in the stent group (65 % vs. 26.3 %; P < 0.05). In terms of the median hospital stay from the time of the procedure to the time of initial discharge home (12 patients vs. nine patients), there was no statistical difference (15 days vs. 30 days) due to the small size of the sample. There was no procedure-related mortality in either group. CONCLUSIONS: Palliative stent placement was more beneficial than surgical gastrojejunostomy in enhancing the quality of life of patients with duodenal obstruction due to pancreaticobiliary malignancies.

Aged↗
PubMed2002

Comparison of inhibitory activity on calcium phosphate precipitation by acidic proline-rich proteins, statherin, and histatin-1.

This study quantitatively compares the inhibition of calcium phosphate (CaP) precipitation by the salivary acidic proline-rich proteins (PRPs) statherin and histatin-1. Saliva and CaCl2 in 125 mM imidazole buffer (pH 7.0) were incubated with potassium phosphate and a hydroxyapatite (HAP) suspension, for 30 min at 25 degrees C, then filtered through nitrocellulose. The calcium (Ca) concentration in the filtrate was measured by atomic absorption spectrophotometry, then deducted from that in the initial solution to determine the amount of CaP precipitation after 30 min. The values of the inhibitory activities on CaP precipitation relative to crude parotid saliva were 4.7, 4.9, 6.9, and 65.8 for histatin-1, large PRPs, small PRPs, and statherin, respectively.

Adult↗
PubMed2002

Gastric bypass model in the obese rat to study metabolic mechanisms of weight loss.

A rat model replicating gastric bypass with Roux-en-Y (GB) as used in morbidly obese patients, evolved in our laboratory in stages, using the Zucker rat as an obese model (GB) is presented. In the final model, a 20% gastric fundic pouch to limit the gastric reservoir was created using two staple lines (Ethicon). A 4- to 5-mm end-to-side gastrojejunostomy and a 6- to 8-mm jejunojejunostomy, at 10 cm length of the Roux-en-Y limb, placed 16 cm below the ligament of Treitz, was hand sewn to create a limited area of nutrient digestion and absorption. Controls underwent sham operation. Rats were divided into: (i) sham-op ad lib-fed (Control); (ii) GB; and (iii) sham-op pair fed (PF) in two experiments. In Experiment 1, 24 Zuckers (control n = 8; GB n = 8; PF n = 8) were studied to assess the effectiveness of the model for weight loss. In Experiment 2, 24 Zuckers (8/group) were studied to confirm the effects of the operation on weight loss and on metabolic parameters. Boost was given for 4 days starting 24 h postop and then ground chow was given. Daily food intake (FI), meal size (MZ), meal number (MN), and body weight (BW) were measured. Rats were sacrificed on Day 20 in Experiment 1 and on Day 10 in Experiment 2. Serum metabolites and body fat weight were measured. Data were evaluated using Student's t test. Controls steadily gained BW (5.2-6.1 g/day), reaching approximately 500 g. In GB: FI, MZ, MN, BW, glucose, free fatty acids, insulin, and body fat decreased (P < 0.05). In PF: BW, insulin, triglycerides, and body fat decreased. A dependable, reproducible gastric bypass with Roux-en-Y obesity model was developed. This permits the study of biochemical and eventually molecular mechanism(s) of weight loss resulting from the operation.

Adipose Tissue↗
PubMed2002

Breast conserving treatment without radiotherapy.

Radiotherapy (RT) is not always necessary for the prevention of ipsilateral breast recurrence in cases where cancer is not detected in the remaining breast tissue after breast conserving surgery. In addition, under these circumstances, the rate of a second primary cancer of the remaining breast is theoretically equal to the rate of contralateral breast cancer. In performing breast conserving treatment (BCT) at our institution we do not treat with RT if a strict serial pathological examination of the specimen (every 5 mm) reveals that the case has been safely resected (negative surgical margins). From 1986 to 1998, 827 patients (157 were ductal carcinoma in situ, and 670 were invasive) underwent BCT without RT at the Cancer Institute Hospital. Ipsilateral breast cancer was observed in 46 cases or 5.6% (0.85% annually) during a median observation period of 67 months. Of these 46 cases, 19 (2.3%) were diagnosed as a recurrence and 27 cases (3.3%) were second primary cancers. This recurrence rate is equivalent to the rate observed in 406 cases of BCT (1.7%) that were treated with RT. Most of these cases had shown positive surgical margins. Furthermore, the rate of occurrence of second cancers is not significantly different from the rate of occurrence of contralateral breast cancers. These results suggest that, by selecting irradiation cases based on careful pathological examinations, BCT can be safely performed.

Breast Neoplasms↗
PubMed2002

Abnormal conditioning effect of transcranial magnetic stimulation on soleus H-reflex during voluntary movement in Parkinson's disease.

OBJECTIVES: The objective of this study is to clarify the participation of cortical motor control abnormality in the motor dysfunction of Parkinson's disease (PD), especially at the onset of movement. METHODS: Conditioning effects of transcranial magnetic simulation (TMS) on the soleus (SOL) H-reflex evoked with tibial nerve stimulation were examined in 19 patients with PD and 10 normal volunteers. Experiments were done at rest, during tonic plantarflexion (PF), and at PF onset. Stimulus intensity of TMS was maintained at less than 5% of the motor threshold in each situation. Seven patients underwent pallidotomy and were examined twice, once before and once after the operation. RESULTS: Short latency subthreshold TMS stimulation did not facilitate the SOL H-reflex neither during tonic PF nor at PF onset in the patients with PD, though it was evident in normal subjects. In some patients, paradoxical inhibition appeared at PF onset. The facilitation increase at PF onset, as compared to that at rest, was negatively correlated with the motor part of the unified Parkinson's disease rating scale and with the rigidity grade. Pallidotomy improved both modulation and the clinical scores. CONCLUSIONS: Cortical activity for the proper execution of reciprocal control between the agonist and antagonist seems to be disturbed in PD.

Aged↗
PubMed2002

Technical modifications and strategies for stenting gastric outlet strictures using esophageal endoprostheses.

BACKGROUND AND STUDY AIMS: The outcome of stenting gastric outlet stricture is favorable compared with a bypass operation which has significant morbidity and mortality. In Japan, this procedure is particularly complicated by a lack of enteral stents. We report some technical stratagems for stent placement for gastric outlet strictures. PATIENTS AND METHODS: Between February 1993 and July 2001, 23 patients with gastric outlet strictures (14 men, nine women; mean age 72 years) underwent stent placement using an esophageal stent system. The Ultraflex or Z-stents were used in 18 or five patients, respectively. With the Ultraflex, we increased the length of the delivery system. Some patients underwent stent placement with the help of endoscopic assistance with a grasping forceps or a home-made sheath. RESULTS: The metal stent was successfully inserted in all patients. There were no complications during the procedure. Migration occurred in two out of five patients treated with the Z-stent, whereas there was no migration in patients treated with the Ultraflex stent. In two patients, curable pancreatitis was caused by pressure on the duodenal papilla. One of these patients also experienced bile stasis which required biliary decompression. There were three cases of obstruction, caused by tumor ingrowth (1), hyperplasia (1) and stent fracture (1); recanalization by an additional stent placement and/or cutting stent filaments was successful. All the patients died, with a median survival period of 52 days. There was no procedure-related mortality. CONCLUSIONS: With some technical modification, stent placement for gastric outlet stricture, even using an esophageal stent, is feasible. This procedure offers good palliation with no major complications.

Adult↗
PubMed2002

A new cannula with a flexible tip (Swing Tip) may improve the success rate of endoscopic retrograde cholangiopancreatography.

BACKGROUND AND STUDY AIMS: Endoscopic retrograde cholangiopancreatography (ERCP) is sometimes unsuccessful because the anatomy of the papilla of Vater precludes cannulation by routine means. The efficacy of a new flexible tip cannula (the Swing Tip) was studied in patients in whom routine ERCP was unsuccessful. PATIENTS AND METHODS: The Swing Tip cholangiographic catheter has an articulation at its tip which allows the tip to be flexed from 90 degrees to 30 degrees. Routine cholangiography was successful in 175 of 195 patients in whom it was attempted between September 2000 and November 2001. ERCP with the Swing Tip catheter was attempted in the 20 patients in whom ERCP had failed. RESULTS: In 17 of 20 patients, we attempted to insert the Swing Tip catheter into the common bile duct to perform cholangiography. Insertion was successful in 11 patients and unsuccessful in six. There were no complications related to the procedure. CONCLUSION: The Swing Tip catheter is a useful adjunct to standard ERCP catheters for patient in whom standard techniques are unsuccessful.

Bile Duct Diseases↗
PubMed2002

Chromatin reprogramming of male somatic cell-derived XIST and TSIX in ES hybrid cells.

In mammalian somatic cells, the X chromosome is active in XY males, whereas one X chromosome is inactivated in XX females. On the active male X chromosome, the XIST and TSIX genes are transcribed in undifferentiated cells of pre-implantation embryos (undifferentiated state) and then down-regulated upon cell differentiation (differentiated state). To explore the epigenetic mechanism involved in the on-off switching of XIST and TSIX transcription in the active X chromosome, male somatic cells were hybridized with male embryonic stem (ES) cells. Fluorescence in situ hybridization analysis revealed that the XIST gene derived from somatic cells was derepressed, as shown by the advent of two pinpoint signals. This was confirmed by strand-specific RT-PCR of XIST and TSIX genes. To analyze changes in chromatin structure in the promoter regions of XIST and TSIX derived from somatic cells, histone tail modifications were studied by chromatin immunoprecipitation analysis. Histones H3 and H4, which were hypoacetylated in the somatic cells, were hyperacetylated in the hybrid cells, and histone H3 lysine 4, which was hypomethylated in the somatic cells, was hypermethylated in the hybrid cells, indicating that the reactivation of XIST and TSIX was linked with chromatin modifications. In the telomeric region of DXPAS34, acetylation of histones H3 and H4 was dependent on reactivation of XIST and TSIX, whereas histone H3 lysine 4 was constitutively methylated independent of the transcriptional activity of those genes. We propose that the chromatin reprogramming is linked with the resetting of the memory found in the process of choosing an active X chromosome.

Animals↗
PubMed2001

Expression of glia maturation factor during retinal development in the rat.

Glia maturation factor plays important roles in the development and growth of glia and neurons. We investigated the expression and localization of Glia maturation factor-beta (GMFB) and Glia maturation factor-gamma (GMFG) in the rat retina. By northern blot analysis, both GMFB and GMFG mRNAs were detected in retina as early as embryonic day (E) 18 and persisted until adult. The expression of GMFB mRNA was always much greater than that of GMFG mRNA. In situ hybridization showed that the GMFB mRNA signal was positive in the retina from E14 till adult. Immunostaining revealed that GMFB protein was present in the inner layer of retina at E14 and P1, and in Müller cells in adult. GMFG immunoreactivity was observed only in the inner limiting membrane from E14 to P1 rat retina, and was not detected in the adult retina. These results show that GMFs are synthesized and localized mainly in Müller cells in the rat retina, and suggest that they may contribute to the development and growth of glia and neurons.

Animals↗
PubMed2001

Nuclear reprogramming of somatic cells by in vitro hybridization with ES cells.

The resetting of a somatic epigenotype to a totipotential state has been demonstrated by successful animal cloning, via transplantation of somatic nuclei into enucleated oocytes. We have established an experimental system, which reproduces the nuclear reprogramming of somatic cells in vitro by fusing adult thymocytes with embryonic stem (ES) cells. Analysis of the lymphoid-cell-specific V-(D)-J DNA rearrangement of the T cell receptor and immunoglobin genes shows that the ES cells have hybridized with differentiated cells. In these ES cell hybrids, the inactivated X chromosome derived from a female thymocyte adopts some characteristics of an active X chromosome, including early replication timing and unstable Xist transcription. We also found that an Oct4-GFP transgene, which is normally repressed in thymocytes, is reactivated 48 hr after cell fusion. The pluripotency of the ES-thymocyte hybrid cells is shown in vivo, since they contribute to all three primary germ layers of chimeric embryos. The somatic DNA methylation pattern of the imprinted H19 and Igf2r genes is maintained in these hybrids, unlike hybrids between ES and EG (embryonic germ) cells in which the differential methylation is erased. Thus, ES cells have the capacity to reset certain aspects of the epigenotype of somatic cells to those of ES cells.

Animals↗
PubMed2001

Cholesteryl ester transfer protein deficiency causes slow egg embryonation of Schistosoma japonicum.

In our attempt to discover a potential cause for accumulation of cholesteryl ester transfer protein (CETP) deficiency in Eastern Asia, we studied the association of CETP deficiency with pathogenesis of Schistosoma japonicum, a life-threatening parasite peculiar to this region. The eggs of S. japonicum showed slow embryonation when cultured in CETP-deficient human plasma. Restoration of CETP to the deficient plasma rescued it, while inhibition of CETP in normal plasma did not cause slow embryonation of the cultured eggs. The egg embryonation was also retarded in the liver but not in the intestine of wild-type mice in comparison to the CETP-transgenic mice. The granulomatous lesion around the parasite eggs in the liver was less in the wild-type than in the CETP-transgenic mice. Thus, CETP deficiency may act against Schistosomiasis japonica by retarding egg embryonation, a potential cause of liver granulomatosis. It does not seem directly due to the lack of CETP activity in plasma but to abnormal lipoprotein generated by chronic CETP deficiency.

Animals↗
PubMed2001

Crystallization and preliminary X-ray diffraction analysis of NADP-dependent glyceraldehyde-3-phosphate dehydrogenase of Synechococcus PCC 7942.

The NADP-dependent glyceraldehyde-3-phosphate dehydrogenase (GAPDH) of Synechococcus PCC 7942 was crystallized in two different forms by the hanging-drop vapour-diffusion method using ammonium sulfate as a precipitant. Form I crystals were hexagonal, space group P6(5) or P6(1), with unit-cell parameters a = b = 91.1, c = 428.6 A, gamma = 120 degrees. Form II crystals were monoclinic, space group C2, with unit-cell parameters a = 152.3, b = 80.9, c = 213.6 A, beta = 103.1 degrees. Native data were collected from a frozen crystal of form I to a resolution of 2.8 A using synchrotron radiation at SPring-8, whereas form II crystals were easily damaged by radiation at room temperature and increased mosaicity in cryoprotectant solutions. A molecular-replacement solution of the form I crystal was obtained in space group P6(5) using the program AMoRe and the structure of the NAD-dependent GAPDH from Bacillus stearothermophilus.

Crystallization↗
PubMed2001

Alterations in the expression of the AQP family in cultured rat astrocytes during hypoxia and reoxygenation.

Aquaporins (AQPs) are a family of water-selective transporting proteins with homology to the major intrinsic protein (MIP) of lens [Cell 39 (1984) 49], that increase plasma membrane water permeability in secretory and absorptive cells. In the central nervous system (CNS), we detected the transcripts of AQP3, 5 and 8 in addition to the previously reported transcripts of AQP4 and 9 in astrocytes, of AQP3, 5 and 8 in neurons, of AQP8 in oligodendrocytes, and none of them in microglia using RNase protection assay and the reverse transcription-polymerase chain reaction (RT-PCR). Hypoxia evoked a marked decrease in the expression levels of AQP4, 5 and 9, but not of AQP3 and 8 mRNAs, and in astrocytes in vitro subsequent reoxygenation elicited the restoration of the expression of AQP4 and 9 to their basal levels. Interestingly, AQP5 showed a transient up-regulation (about 3-fold) and subsequent down-regulation of its expression within 20 h of reoxygenation after hypoxia. The changes in the profiles of AQP expression during hypoxia and reoxygenation were also observed by Western blot analysis. These results suggest that AQP5 may be one of the candidates for inducing the intracranial edema in the CNS after ischemia injury.

Animals↗
PubMed2001

Characterization of monoclonal antibodies against ascorbate peroxidase isoenzymes: purification and epitope-mapping using immunoaffinity column chromatography.

We have developed three monoclonal antibodies against spinach chloroplastic (chl-mAb3 and chl-mAb6) and cytosolic (cyt-mAb1) ascorbate peroxidase (APX) isoenzymes to analyze the cross-reactivity and the structure of the epitopes for each monoclonal antibody. All three antibodies reacted specifically with their respective isoenzymes, but none cross-reacted with the others. Immunoreactive fragments in proteolytic recombinant APX isoenzymes were detected by means of the absorption on the corresponding immunoaffinity column. The cyt-mAb1 reacted with a peptide fragment containing the distal His region obtained by the lysyl endopeptidase digestion. The chl-mAb6 was capable of binding to the fragment, D-I-K-E-K-R, which is consistent with an inherent region of chloroplastic isoenzymes. No fragments reacting to the chl-mAb3 could be found in this study, suggesting that the chl-mAb3 recognizes a conformationally constituted epitope of the chloroplastic APX molecule, which may be destroyed by the enzymatic cleavage. We concluded that the peptides identified as epitopes are characteristic evidence of monoclonal antibodies.

Amino Acid Sequence↗
PubMed2001

Regulation of aquaporin-4 expression in astrocytes.

Aquaporin-4 (AQP4), a mercury-insensitive water channel protein, is abundant in the central nervous system and is localized in astrocytes and ependymal cells. AQP4 is speculated to maintain the homeostasis of intracellular and extracellular water in the brain, but little is known about the mechanism of induction of its expression. To investigate the expressional regulation of AQP4, we analyzed changes in its expression during chemically induced differentiation of embryonal carcinoma cells (P19) to neuronal and astrocytic cells, and during the cell cycle of glioma cells. After exposure to retinoic acid for 4 days AQP4 mRNA expression started at the initiation of astrocytic differentiation of P19 cells at 6 days, and increased markedly by 21 days. AQP4 expression was parallel to that of GFAP, a marker intermediate filament of astrocytes. In glioma cell lines, AQP4 mRNA was not detected in the growing phase, but was induced when the cell cycle was arrested at G0/G1 by transient expression of p21. Although quiescent astrocytes in the G0/G1-phase cultured under the serum-free condition exhibited a high expression of AQP4, serum supplement moved them to the S-phase and markedly decreased the AQP expression. These results suggest that AQP4 expression may be induced not only at the initiation of astrocytic differentiation of neural stem cells, but also at the G0/G1-phase during the cell cycle of astrocytes.

Animals↗