Search PubMed⌕ Search

Biomedical subjects

T Yamaguchi

Publications and source records attributed to T Yamaguchi.

At least 73 records · Page 4Linked to original sources
PubMed2004

Effect of flow disturbances remaining at the beginning of diastole on intraventricular diastolic flow and colour M-mode Doppler echocardiograms.

A computational model of the fluid dynamics of intraventricular flow was used to investigate the importance of the effects of flow disturbances existing within the left ventricle (LV) at the onset of diastole on a diastolic flow field. The simulation started with a quiescent flow state; it continued for a number of cardiac cycles to obtain a cyclically repeatable flow. After the flow became periodic, the initial diastolic flow was not quiescent: flow disturbances, remnants of a systolic flow, were present within the LV. Nevertheless, they faded away during an acceleration phase of diastole and almost ceased by the end of this phase. Consequently, a flow field during a deceleration phase of diastole, characterised by the formation of a vortex ring, was hardly affected by the initial flow disturbances. The propagation velocity of a colour M-mode Doppler echocardiogram obtained by scanning velocity along the LV long axis was 0.58 m s(-1) in the case where diastolic flow was initially quiescent and 0.56 m s(-1) in the case where flow disturbances existed at the beginning of diastole. These results indicated that the colour M-mode Doppler echocardiographic technique captures flow dynamics produced purely by ventricular expansion, with little influence from initial diastolic flow disturbances.

Computer Simulation↗
PubMed2004

Distribution and characterization of hemolytic activity by an oral anaerobe from the Streptococcus milleri group.

Some oral anaerobes from the Streptococcus milleri strain group were found to secrete human specific hemolytic toxin, which was detected when bacteria were cultured in Todd-Hewitt broth and Brain Heart Infusion broth. The toxin elicited by the Streptococcus intermedius strain was partially fractionated by ammonium sulfate precipitation. Preincubation with glutathione or cysteine showed significant inhibiting effects; however, no effects were seen with dithiothreitol or beta-mercaptoethanol, and cholesterol was a weak inhibitor. Five kinds of protease inhibitor had no effect on the hemolytic activity, and rabbit preimmune and immune sera against the bacterial cells showed weak inhibition at a similar level. Digestion with trypsin, chymotrypsin, proteinase-K, subtilisin and pronase-P brought about a rise in activity, followed by a decrease during long-term incubation. Other enzymes tested showed no effects. Further, the presence of the intermedilysin gene in the portion with hemolytic activity was not identified by polymerase chain reaction.

Adult↗
PubMed2004

Prognostic significance of hepatocyte growth factor and c-MET expression in patients with diffuse large B-cell lymphoma.

The expression and prognostic significance of hepatocyte growth factor (HGF) and its receptor c-MET (MET proto-oncogene) was analysed in 96 cases of diffuse large B-cell lymphoma (DLBCL). Tissue sections were immunohistochemically stained for HGF and c-Met. The prognosis of HGF-positive and c-Met-positive cases was significantly worse than negative cases (HGF: P = 0.0036; c-Met: P = 0.0002). In addition, in the low-risk international prognostic index group, HGF-negative and c-Met-negative cases had a significantly better prognosis than positive cases (HGF: P = 0.0009; c-Met: P < 0.0001). Our results suggest that HGF/c-MET is a useful clinical marker of prognosis for patients with DLBCL.

Adolescent↗
PubMed2004

Cholecystokinin-1 receptor protein up-regulation during pancreatic regeneration after acute haemorrhagic pancreatitis in rats.

BACKGROUND: Cholecystokinin (CCK) plays an important role in regeneration after acute pancreatitis in rats. The present study was aimed to elucidate the role of CCK-1 receptor (CCK-1R) in acute pancreatitis. We investigated the serial changes in CCK-1R mRNA and protein levels and their immunolocalization after acute haemorrhagic pancreatitis induced in male Wistar rats by retrograde intraductal infusion of 4% sodium taurocholate (100 micro L 100 g(-1) body weight). METHODS: Histological changes were evaluated by haematoxylin and eosin staining. Pancreatic CCK-1R mRNA was determined by Northern blot analysis. Pancreatic CCK-1R protein was evaluated by immunoblot analysis and immunohistochemistry with a polyclonal antibody against rat CCK-1R protein. RESULTS: Histological findings revealed that newly formed acinar cells were detected at the periphery of tubular complexes on day 14, and normal architecture of lobules was observed focally on day 21. Pancreatic CCK-1R mRNA peaked on day 3 and thereafter gradually decreased. Cholecystokinin-1R protein rapidly increased after induction of pancreatitits, reaching a maximal level on day 3. On day 3, intense immunoreactivity for CCK-1R protein was observed in both the cytoplasm of vacuolized acinar cells and the tubular complexes. In the regenerative process after acute haemorrhagic pancreatitis in rats, the expression of pancreatic CCK-1R mRNA and protein increased, and intense immunoreactivity for CCK-1R protein was observed in tubular complexes in the cytoplasm of regenerated acinar cells. CONCLUSION: These results suggest that CCK-1R contributes to pancreatic regeneration after acute haemorrhagic pancreatitis and that tubular complexes are involved in the process of acinar cell regeneration following pancreatic injury.

Acute Disease↗
PubMed2004

Intraosseous benign notochordal cell tumours: overlooked precursors of classic chordomas?

AIMS: Intraosseous benign notochordal cell tumour is a recently recognized condition that may undergo malignant transformation to classic chordoma. The aim of this study was to describe its clinicopathological characteristics. METHODS AND RESULTS: One hundred vertebral columns from atlas to coccyx and 61 pieces of the clival portion of the skull base, which were dissected from 100 autopsy cases, were examined microscopically. Twenty-six intraosseous benign notochordal cell tumours were found in 20 cases. The patient group consisted of 15 males and five females with a mean age of 63 years. The results, according to anatomical segments, showed that 11.5% of the clivus, 5.0% of the cervical vertebrae, 0% of the thoracic vertebrae, 2.0% of the lumbar vertebrae, and 12.0% of the sacro-coccygeal vertebrae were affected. Microscopic examination revealed well demarcated but unencapsulated sheets of bland physaliphorous cells mimicking adipocytes. The lesions lacked any intercellular myxoid matrix. The affected bone trabeculae were characteristically sclerotic. CONCLUSIONS: The study indicated a surprisingly high incidence of intraosseous benign notochordal cell tumours. The anatomical distribution of the tumours was identical to that of classic chordomas. The results support other evidence that classic chordomas develop from intraosseous benign notochordal cell tumours.

Age Factors↗
PubMed2004

Gene expression profiling of mouse condylar cartilage during mastication by means of laser microdissection and cDNA array.

Little is known about the mechanisms of mandibular condylar growth. In this study, gene expression in the mandibular condylar cartilage of young post-natal mice was monitored by means of a cDNA microarray, real-time PCR, and laser microdissection before and after the initiation of mastication (newborn, 7 days, 21 days, initiation of mastication, and 35 days). Insulin-like growth factor-1 (IGF-I), transforming-growth-factor-beta-2 (TGFbeta2), and aggrecan mRNAs were clearly expressed at 21 days, while the expression of osteopontin mRNAs was most clear at 35 days. Parathyroid-hormone-related protein (PTHrP), Indian-hedgehog (Ihh), and insulin-like growth factor-2 (IGF-2) mRNAs were clearly expressed during lactation (newborn and 7 days). Heat-shock-protein 84 (HSP-84) and heat-shock-protein 86 (HSP-86) were clearly expressed at 35 days. These results revealed that gene expression changed during mandibular condylar cartilage growth, and that, interestingly, these changes coincided with the initiation of mastication.

Aggrecans↗
PubMed2004

Cementless total hip arthroplasty using an autograft of the femoral head for marked acetabular dysplasia: case series.

PURPOSE: To assess the short-term outcome of cementless total hip arthroplasty involving an autograft of the femoral head in Japanese patients. METHODS: Cementless total hip arthroplasty with autogenous bone block grafting was performed on 18 hips in 15 patients with marked acetabular dysplasia. The resected femoral head was used as a graft for the superior-lateral region of the true acetabulum. Clinical outcome was correlated with the placement of the acetabular component, as revealed in radiographs. RESULTS: The 13 women and 2 men had a mean age of 60.2 years (range, 37.0-73.0 years) at primary surgery and a mean follow-up duration of 3.3 years (range, 2.0-5.3 years). According to the classification of Crowe, 4 hips were in group I, 3 were in group II, one in group III, and 10 in group IV. The mean Harris Hip Score preoperatively was 45.7 (range, 19-69) and that at follow-up was 82.5 (range, 44-100). All 15 cases showed a good clinical outcome. There were no major intra-operative complications in this series. The grafted bones united in all patients. Two patients need surgical revision because the lateral insertion of the acetabular component resulted in loosening of it. CONCLUSION: Medial insertion of the acetabular component provides satisfactory short-term outcomes. Lateral insertion of the acetabular component during total hip arthroplasty should be avoided in patients with marked acetabular dysplasia.

Acetabulum↗
PubMed2004

Total hip arthroplasty: the relationship between posterolateral reconstruction, abductor muscle strength, and femoral offset.

PURPOSE: To evaluate the relationship between posterolateral reconstruction, abductor muscle strength, and femoral offset following total hip arthroplasty. METHODS: Of 28 patients (56 limbs) we assessed, 12 underwent posterolateral reconstruction (reconstruction group) and 16 did not (non-reconstruction group). Isometric abductor muscle strength was measured with a handheld dynamometer. Each patient's muscle strength was converted into a force to body weight ratio, and this ratio was used in the comparisons. RESULTS: The reconstruction group showed a higher value in abductor muscle strength than the non-reconstruction group (p<0.05). Significant correlation between abductor muscle strength and femoral offset was found in the reconstruction group (p=0.016; r=0.674). CONCLUSION: Posterolateral reconstruction and appropriate reconstruction of femoral offset following total hip arthroplasty are important to improve the abductor muscle strength.

Aged↗
PubMed2004

Treatment of gastric hemorrhage by pulverized omeprazole and antacid--concomitant administration via a nasogastric tube.

Gastroesophageal reflux (GER) is a common episode in pediatric patients with severe motor and intellectual disabilities (SMID) and occasionally leads to a severe clinical state accompanied with nausea, hematemesis, melena, wheezing, pneumonia, anemia and/or failure to thrive. We report here a case of a 14-year-old male with Lennox syndrome who had been treated with a histamine H2 blocker intravenously or via a nasogastric tube for repeated gastric hemorrhage due to severe GER. Since his gastric hemorrhage became resistant to the H2 blocker, we decided to replace it with a proton pump inhibitor (PPI). Although lansoprazole can be decapsulated for administration via a nasogastric tube, it tends to block fine tubes. The acid-sensitive drug omeprazole, another oral PPI, is commercially available as enteric-coated tablets. Therefore, we pulverized the tablets and administered omeprazole, mixed with a small amount of antacid, via a nasogastric tube. The patient's gastric hemorrhage was dramatically improved. Thus, administration of pulverized omeprazole concomitantly with antacid via a fine nasogastric tube may provide a novel approach for the treatment of chronic GER in pediatric patients with SMID.

Adolescent↗
PubMed2004

Hyperbaric oxygen therapy in orthopedic conditions.

As is well known, the origins and development of hyperbaric medicine are closely tied to the history of diving medicine. Our HBO2 studies stemming from diving medicine date back to 1972. We concentrated our early basic research on dysbaric osteonecrosis. There are now good indications that HBO2 is helpful in a variety of orthopedic conditions. However, hyperbaric medicine in orthopedics is still relatively new and some aspects of it remain controversial.

Congresses as Topic↗
PubMed2004

[Surgical treatment of traumatic disruption of the thoracic aorta due to fall from 6 meters height tree; report of a case].

Disruption of the thoracic aorta due to blunt chest trauma is highly lethal and requires emergent operative intervention. A successful operative treatment of traumatic disruption of the thoracic aorta is reported. A 44-year-old male was admitted to our hospital following a fall from 6 m height tree. Four hours after accident, chest X-ray film demonstrated mediastinal widening. Chest helical computed tomography (CT) scanning demonstrated mediastinal hematoma, left pleural effusion and partial descending aortic dissection. Aortic disruption was diagnosed, and surgery for the thoracic aorta was performed emergently. The 2/3 of circumferentia of the aorta was found to be disrupted in the length of 2 cm, and it was replaced with a vascular prosthesis under partial cardiopulmonary bypass. We conclude that the enhanced chest helical CT scanning is helpful for diagnosis and that if other organ injuries are not critical, the emergent surgery should be required.

Accidental Falls↗
PubMed2004

Quantification of amoA gene abundance and their amoA mRNA levels in activated sludge by real-time PCR.

The transcription level of amoA mRNA encoding a subunit of ammonia monooxygenase (AMO) in ammonia-oxidizing bacteria (AOB) was quantified by reverse transcription-polymerase chain reaction (RT-PCR) methods in combination with real-time PCR technology. The effects of ammonia concentration and dissolved oxygen (DO) on the transcription levels of amoA mRNA and 16S rRNA in AOB were evaluated in batch experiments with nitrifying sludge taken from a lab-scale reactor treating artificial wastewater. A batch incubation without ammonia resulted in a rapid decrease, within four hours, in the transcription level of amoA mRNA to as low as 1/10 of that at the beginning of the experiment, while the 16S rRNA level in AOB was almost constant. After subsequent incubation with 3 mM ammonia for eight hours, a small increase in the transcription level of amoA mRNA occurred, but ammonia oxidation proceeded in the interim. Copy numbers of amoA mRNA showed an almost fixed value for over eight hours in the absence of dissolved oxygen.

Ammonia↗
PubMed2003

Edg-8 receptors are preferentially expressed in oligodendrocyte lineage cells of the rat CNS.

The messenger RNA for endothelial differentiation gene 8 receptors is known to be expressed almost exclusively in the rat CNS, but the nature of the expressing cells has not been defined. Using an antibody specific for endothelial differentiation gene 8, we investigated the immunohistochemical localization of endothelial differentiation gene 8 receptors in the rat CNS. Immunopositive staining was detected in a subset of glial cells distributed throughout the brain and spinal cord, including both gray and white matter, but not in the dorsal root ganglion. The distribution and morphological similarity in comparative immunostaining for endothelial differentiation gene 8 and various glial markers suggested that endothelial differentiation gene 8 is preferentially expressed in NG2-positive oligodendrocyte progenitor cells in adult rat brains. Counts of endothelial differentiation gene 8-positive cells and NG2-positive cells in the forebrain revealed that a subset of NG2-positive cells was endothelial differentiation gene 8-positive, and that the ratio of endothelial differentiation gene 8-positive cells to NG2-positive cells varied from region to region. In 17-day-old embryonic brains, the endothelial differentiation gene 8 distribution was similar to that of an oligodendrocytic marker, 2',3'-cyclic nucleotide 3'-phosphodiesterase. These data suggest that endothelial differentiation gene 8 receptors are preferentially expressed in oligodendrocyte lineage cells including oligodendrocyte progenitor cells and immature/maturating oligodendrocytes in rat CNS, and that they might have important functions in oligodendrocytic maturation and myelination.

Animals↗