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Biomedical subjects

S Yoshida

Publications and source records attributed to S Yoshida.

At least 91 records · Page 5Linked to original sources
PubMed2002

Evaluation of esophageal motility by endosonography using a miniature ultrasonographic probe in patients with reflux esophagitis.

BACKGROUND: Although there are several established methods used to evaluate esophageal motility, none allows for direct observation of esophageal wall motion. Esophageal dysmotility is thought to contribute to reflux esophagitis (RE). The aim of this study was to evaluate esophageal wall motility by endosonography using a miniature ultrasonographic probe (MUP) in patients with RE. METHODS: The subjects consisted of 10 healthy controls (10 men with a mean age of 31.5 years) and 9 patients with RE (4 men and 5 women with a mean age of 51.5 years). High-frequency endoluminal sonography was performed using a 20-MHz transducer through a 16F gastric tube to evaluate esophageal wall motion. Four sonographic phases of an esophageal peristaltic sequence were identified. In the resting phase, the esophageal wall was in direct contact with the transducer. In the passive distention phase, the esophageal lumen was stretched maximally; in the contraction phase, it contracted; and in the relaxation phase, it returned to baseline. The baseline thickness of the muscle layers of the esophageal wall was measured at rest. The width decreased during the passive distention phase, increased and reached a maximum during the contraction phase, and returned to baseline during the relaxation phase. RESULTS: The contractility index of the circular smooth muscle (CSM) in the distal esophagus and of the longitudinal smooth muscle (LSM) in the proximal esophagus were significantly lower in patients with RE. The duration of contraction in the distal esophagus was significantly longer in RE. CONCLUSIONS: We used a MUP to demonstrate abnormalities in esophageal wall motility in patients with RE. We conclude that the MUP is a potentially useful technique for evaluating esophageal dysmotility.

Adult↗
PubMed2002

Evaluation of gastric emptying measured with the 13C-octanoic acid breath test in patients with functional dyspepsia: comparison with ultrasonography.

BACKGROUND: As a non-invasive modality by which to evaluate the gastric emptying of a solid meal, the 13C-octanoic acid breath test has recently become more widely used. Previously, we reported that ultrasonography was another non-invasive and reliable method for assessing gastric motility. The aim of this study was to compare the reliability of these two methods. METHODS: Seventeen patients with functional dyspepsia and 10 healthy volunteers were studied. The solid test meal consisted of a scrambled egg labeled with 13C-octanoic acid (100 mg) and served with a bowl of rice and boiled chicken (total 424 kcal). After ingestion of the test meal, all subjects were examined in the sitting position. Ultrasonography images were obtained every 15 min for 3 h. Breath sampling followed the same time schedule as for the ultrasonography, with an additional 3 h of sampling at 30-min intervals. We investigated the half emptying time (T1/2) and the lag phase with both methods. RESULTS: The T1/2 by the ultrasonography method and the breath test were positively correlated (r2 = 0.638); however, there was no significant agreement between the study groups. Both the T1/2 and the lag phase were prolonged in the functional dyspepsia patients compared with the healthy volunteers, regardless of the method of measurement. The lag phase was significantly correlated (r2=0.864) with the T1/2 by the breath test. CONCLUSIONS: Although the 13C-octanoic acid breath test cannot assess the gastric emptying of solids as reliably as ultrasonography, both tests are useful for evaluating functional dyspepsia patients with delayed gastric emptying.

Adolescent↗
PubMed2002

Preoperative assessment of gastric cancer vascularity by flash echo imaging.

BACKGROUND: Tumor vascularity as indicated by immunohistochemical staining is a significant prognostic factor in gastric and other cancers. Non-invasive preoperative assessment of the vascularity of gastric cancers has not been possible. We aim to determine the reliability of harmonic flash echo imaging (FEI) for assessment of vascularity of gastric cancers by comparison with CD34 staining of resected specimens. METHODS: Twelve patients undergoing surgical resection of advanced gastric cancer were studied. An ultrasound system transmitting ultrasound pulses at 2.3 MHz and receiving them at 4.6 MHz (second harmonic image) was used for harmonic FEI. Approximately 30 s after intravenous injection of ultrasonic contrast medium (SHU 508A, Levovist), second harmonics (4.6 MHz) emitted from microbubbles were obtained to enhance the B-mode images. Using the tumor image showing strongest enhancement in each FEI series, regions of interest were determined to measure mean echo intensity in the tumor. Immunohistochemistry using antibodies against CD34 was carried out in resected specimens. Tumor vascularity was determined by counting stained microvessels. RESULTS: A significant positive correlation was noted between sonographic amplitude determined preoperatively by FEI analysis and number of CD34-stained microvessels in tumor specimens (r = 0.869, P = 0.004). CONCLUSION: Vascularity of gastric cancers now can be evaluated non-invasively by harmonic FEI.

Antigens, CD34↗
PubMed2002

Epidermal expression of serine protease, neuropsin (KLK8) in normal and pathological skin samples.

AIMS: The expression of human neuropsin (KLK8) mRNA in normal and pathological skin samples was analysed and the results compared with those for tissue plasminogen activator (tPA) mRNA. METHODS: Northern blot and in situ hybridisation analyses of KLK8 mRNA in normal and lesional skin of patients with cutaneous diseases were performed. RESULTS: A weak signal for KLK8 mRNA and no signal for tPA mRNA was seen in normal skin on northern blot analysis. Weak signals for KLK8 were localised to the superficial cells beneath the cornified layer in normal skin on in situ hybridisation. Psoriasis vulgaris, seborrheic keratosis, lichen planus, and squamous cell carcinoma skin samples, which show severe hyperkeratosis, displayed a high density of KLK8 mRNA on northern and in situ hybridisation analyses. The signals were localised in granular and spinous layers of lesional skin in all hyperkeratic samples, including the area surrounding the horn pearls of squamous cell carcinoma. To examine the relation between mRNA expression and terminal differentiation, the expression of KLK8 mRNA was analysed in cell cultures. When keratinisation proceeded in high calcium medium, a correlative increase in the expression of KLK8 mRNA was observed. CONCLUSION: The results are consistent with a role for this protease in the terminal differentiation of keratinocytes.

Adult↗
PubMed2002

Postoperative outcome of lumbar spinal canal stenosis after fenestration: correlation with changes in intradural and extradural tube on magnetic resonance imaging.

PURPOSE: To evaluate the serial changes in clinical results and the intradural and extradural spaces on magnetic resonance imaging (MRI) after bilateral fenestration in 48 patients with lumbar spinal canal stenosis (LSCS). METHODS: A prospective interventional study was performed to study the clinical results, magnetic resonance imaging scans among patients who were followed up for more than 3 years. RESULTS: All patients showed improvement in clinical symptoms after operation, but clinical results deteriorated in 9 (19%) patients. Postoperative MRI scans showed that poor dural tube expansion, grouping of the cauda equina, and decrease in the cross-sectional area of the dural tube were factors associated with poor outcomes. The cross-sectional area of the dural tube and images of the cauda equina observed by MRI, before and after fenestration and during follow-up, reflected changes in clinical symptoms involving decompressed segments. CONCLUSION: Serial changes in the cross-sectional area of the dural tube and images of the cauda equina observed preoperatively, postoperatively, and on follow-up by MRI may be useful when evaluating patients' condition before and after operation. It is also useful for predicting outcomes.

Aged↗
PubMed2002

Combined use of percutaneous ethanol injection and radiofrequency ablation for the effective treatment of hepatocelluar carcinoma.

Radiofrequency ablation (RFA) and percutaneous ethanol injection (PEI) therapy are currently used for the treatment of hepatocellular carcinoma (HCC). The purpose of this study was to evaluate the usefulness of combination therapy of PEI and RFA (PEI-RFA). Seventy-three patients with biopsy-proven HCC and liver cirrhosis underwent RFA after a bolus injection of ethanol into HCC. The volume of coagulated necrosis in the liver caused by PEI-RFA was estimated and compared with that by RFA alone. Coagulated necrosis areas in the liver of patients treated with PEI-RFA were significantly larger than those of patients treated with RFA alone. In PEI-RFA group, the volume of coagulated necrosis was significantly correlated with the amounts of ethanol injected into HCC. No major complications were observed during and after the PEI-RFA treatment. These results indicate that PEI-RFA is more effective than RFA alone and can make dramatic improvement of therapeutic effects in RFA therapy for HCC with fewer sessions of treatments. Therefore, PEI-RFA is considered to be a practical and promising option and may open up new avenues for the treatment of HCC.

Adult↗
PubMed2002

Tuberculous aortitis, ruptured 48 years after therapeutic implantation of synthetic balls.

A case of tuberculous aortitis, ruptured 48 years after an implantation of synthetic balls into the extrapleural space was reported. Those balls were implanted as a therapeutic alternative to artificial pneumothorax for treating pulmonary tuberculosis. Free perforation was triggered by debridement of an expanding cold abscess. A tuberculous abscess adjacent to the arterial wall should be carefully managed even in the absence of the blood flow by image analysis.

Aged↗
PubMed2002

Bronchopleural fistula after lung cancer surgery. Multivariate analysis of risk factors.

BACKGROUND: To elucidate retrospectively the risk factors for bronchopleural fistulae after lung cancer surgery. METHODS: The subjects were 1,177 patients with lung cancer who underwent surgery between 1983 and 1997. Twenty-two clinical factors were examined by logistic analysis. RESULTS: Bronchopleural fistulae were observed in 35 patients (32 males, 3 females) with a mean age of 64 years. Eighteen (51%) of 35 patients died of BPF-related complications. The significant risk factors obtained by univariate analysis were male gender, heavy smoking, current smoking, low level of %FVC, metastases to lymph nodes, squamous cell carcinoma, increased WBC, decreased albumin, advanced postsurgical stage, sleeve lobectomy, and resection of the right lower lobe or middle and lower lobe. The significant risk factors noted by multivariate analysis were heavy smoking (30 or more pack/years), current rather than past smoking, metastases to lymph nodes, decreased albumin (3.5 mg/dl or less), and resection of the right lower lobe or middle and lower lobe. CONCLUSIONS: The above risk factors must be taken into account before surgical techniques followed by adequate perioperative management are selected.

Adolescent↗
PubMed2001

Effects of potassium channel blockers on hyperinflation-induced rapidly adapting pulmonary stretch receptor stimulation in the rabbit.

The effects of K+ channel blockers, such as 4-aminoprydine (4-AP) and tetraethylammonium (TEA), on the excitatory responses of rapidly adapting pulmonary stretch receptor (RAR) activity to hyperinflation (inflation volume=3 tidal volumes) were investigated in anesthetized, artificially ventilated rabbits after vagus nerve section. The changes in the RAR adaptation index (AI) produced by constant-pressure (approximately 30 cmH2O, 29.7+/-0.2 cmH2O) inflation of the lungs were also examined before and after pretreatment with 4-AP and TEA. The administration of 4-AP (0.7 and 2.0 mg/kg) potentiated hyperinflation-induced RAR stimulation in a dose-dependent manner. During hyperinflation after 2.0 mg/kg 4-AP administration the discharge of RARs showed a relatively regular firing pattern in both inflation and deflation phases. The RAR AI values during constant-pressure inflation of the lungs were significantly reduced by 4-AP treatment (2.0 mg/kg). TEA treatment (2.0 and 7.0 mg/kg) did not significantly alter either the excitatory response of RAR activity to hyperinflation or the RAR AI values seen during constant-pressure inflation of the lungs. These results suggest that during hyperinflation in in vivo experiments on rabbits, RARs may be maintained at a lower activity by opening the 4-AP-sensitive K+ channels on the receptor endings, which can determine accommodation of the receptor discharge.

4-Aminopyridine↗
PubMed2001

Changes of oligosaccharides and fatty acids in monkey hippocampus by synaptic potentiation.

We measured the release of free fatty acids and structural changes of glycoprotein glycans induced by tetraethylammonium (TEA) salt in hippocampal slices of cynomolgus monkey brain. The release of free fatty acids in the hippocampal slices occurred after synaptic potentiation by TEA in a different manner from rat hippocampus. Arachidonic acid release in monkey hippocampus occurred much faster than that in rat. Several types of glycans of monkey hippocampal glycoproteins were determined depending on the duration time after TEA treatment. 5-Mannose was increased within 2 min, while polysialoglycans were increased after 5 min or later. Comparative study of glycans of monkey and rat hippocampal slices revealed the presence of relatively larger amount of sialo- and multi-anntenary glycans in rat than in monkey. These results indicate that the depolarizing stimulation of monkey hippocampal slices induced the change of glycoprotein glycan structures and release of free fatty acids in a different manner from rat hippocampus.

Animals↗
PubMed2001

Sgn1, a basic helix-loop-helix transcription factor delineates the salivary gland duct cell lineage in mice.

The salivary system in mammals is comprised of three independently developed pairs of organs, the parotid, submaxillar, and sublingual glands. Each gland is composed of various ductal and acinar cell types that fulfill multiple roles. However, the molecular mechanisms regulating their biogenesis and functions are still largely unknown. In this paper, we report that two class B basic helix-loop-helix (bHLH) transcriptional regulators delineate the ductal and the acinar cells in salivary glands. Sgn1, a novel class B bHLH factor, is specifically expressed in the salivary duct cells, while the acinar cells are characterized by the expression of another class B bHLH factor, Mist1. The molecular nature of Sgn1 was also investigated: it binds to specific sequences of DNA as a dimer with a class A bHLH factor and acts as a negative transcriptional regulator against other bHLH factors. This study provides an important cue towards better understanding of the generation and function of multiple cell types in salivary glands. In addition, Sgn1 expression exhibits a reverse relationship with the development of male phenotypes, suggesting its role in gender dimorphism in the salivary glands.

Amino Acid Sequence↗
PubMed2001

Hypodermal expression of Caenorhabditis elegans TGF-beta type I receptor SMA-6 is essential for the growth and maintenance of body length.

There are several transforming growth factor-beta (TGF-beta) pathways in the nematode Caenorhabditis elegans. One of these pathways regulates body length and is composed of the ligand DBL-1, serine/threonine protein kinase receptors SMA-6 and DAF-4, and cytoplasmic signaling components SMA-2, SMA-3, and SMA-4. To further examine the molecular mechanisms of body-length regulation in the nematode by the TGF-beta pathway, we examined the regional requirement for the type-I receptor SMA-6. Using a SMA-6::GFP (green fluorescent protein) reporter gene, sma-6 was highly expressed in the hypodermis, unlike the type-II receptor DAF-4, which is reported to be ubiquitously expressed. We then examined the ability of SMA-6 expression in different regions of the C. elegans body to rescue the sma-6 phenotype (small) and found that hypodermal expression of SMA-6 is necessary and sufficient for the growth and maintenance of body length. We also demonstrate that GATA sequences in the sma-6 promoter contribute to the hypodermal expression of sma-6.

Animals↗
PubMed2001

Stimulation of DNA polymerase alpha by hypergravity generated by centrifugal acceleration.

Gravity alteration is known to influence cell proliferation. Here we tested the effects of hypergravity on the action of DNA polymerase alpha, one of the DNA replication enzymes in eukaryotes. Hypergravity was produced by horizontal centrifugal acceleration with a hand-made rotator. The reaction rate of DNA polymerase alpha in centrifuge tubes increased along with the acceleration up to 4g, when a plateau was reached. In contrast, no stimulation was observed with primase, DNA polymerase epsilon, and the E. coli DNA polymerase I Klenow fragment. Kinetic analysis of DNA polymerase alpha reactions revealed that, under high gravity conditions, the K(m) value for template DNA decreased while the V(max) stayed constant. In contrast, the centrifugal acceleration did not affect the K(m) values for deoxyribonucleoside triphosphates. These results suggest that the hypergravity enhances the activity of DNA polymerase alpha by increasing the affinity of the enzyme for template DNA. Such enhancement was more prominent with a low concentration of DNA polymerase alpha under low ionic conditions.

Animals↗
PubMed2001

Determination of uranium isotopes in soil core samples collected on the JCO grounds after the criticality accident.

To evaluate the impact of the 1999 criticality accident in Tokai-mura on the U isotope composition in soils, U isotopes (235U and 238U) were determined with inductively coupled plasma-mass spectrometry (ICP-MS) for soil core samples collected on the JCO grounds after the accident. The 235U/238U ratios were higher than the natural ratio in most samples. The highest ratio observed was 0.0262. Although vertical profiles of the 235U/238U ratio differed among the soil cores, the ratios tended to be high at the surface and decreased with depth. The U concentration also changed with depth. The percentages of 235U in the excess U, estimated from the positive correlation between U concentration and the 235U/238U ratio in soil samples, were less than 4% by mass (mostly 1-3%) and were much lower than the enrichment of the U used in the uranium conversion building at the time of the criticality accident (18.8%). These findings indicate that enriched U had been released before the criticality accident during the U processing at JCO in connection with the reconversion of light water reactor fuel. Since the range of the U concentrations found was comparable to the range of uncontaminated Japanese surface soils, the amount of U added to the soil was judged negligible from a radiation protection viewpoint.

Japan↗
PubMed2001

Measurement of 240Pu/239Pu isotopic ratios in soils from the Marshall Islands using ICP-MS.

Nuclear weapons tests conducted by the United States in the Marshall Islands produced significant quantities of regional or tropospheric fallout contamination. Here we report on some preliminary inductively coupled plasma-mass spectrometry (ICP-MS) measurements of plutonium isolated from seven composite soil samples collected from Bikini, Enewetak and Rongelap Atolls in the northern Marshall Islands. These data show that 240Pu/239Pu isotopic signatures in surface soils from the Marshall Island vary significantly and could potentially be used to help quantify the range and extent of fallout deposition (and associated impacts) from specific weapons tests. 137Cs and 60Co were also determined on the same set of soil samples for comparative purposes.

Environmental Monitoring↗
PubMed2001

Arg660Ser mutation in Thermus aquaticus DNA polymerase I suppresses T-->C transitions: implication of wobble base pair formation at the nucleotide incorporation step.

We examined the replication fidelity of an Arg660Ser (R660S) mutant of Thermus aquaticus DNA polymerase I (Taq pol I). In a forward mutation assay, R660S showed a marked reduction in T-->C transitions, one of the most frequent errors made by the wild-type enzyme. Steady-state kinetics showed that R660S discriminates against dGTP incorporation at a template T 13-fold better than the wild-type. R660S was also 3.2-fold less efficient than the wild-type at extending a T:dG mismatch. These results indicate that R660S has enhanced fidelity during incorporation and extension, which reduces its T-->C transition frequency. Interestingly, R660S also discriminated correct from incorrect nucleotides at the incorporation step of C:dATP, A:dATP, G:dATP and C:8-OH-dGTP mispairs 28-, 6.0-, 4.1- and 6.8-fold better, respectively, than the wild-type, although it may not always be as accurate as the wild-type at the extension step. A structural model suggests that Arg660 may participate in two interactions that influence fidelity; the guanidinium group of Arg660 might interact with the incoming guanine base at the major groove and it might compete for forming another interaction with the primer terminus. Substituting Arg with Ser may eliminate or alter these interactions and destabilize the closed complex with incorrect substrates. Our data also suggest that T:dGTP and C:dATP base pairs form 'wobble' structures at the incorporation step of Taq pol I.

Arginine↗