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Biomedical subjects

K Yasuda

Publications and source records attributed to K Yasuda.

At least 469 records · Page 26Linked to original sources
PubMed1997

Interferon-alpha therapy in patients dually infected with hepatitis C virus and GB virus C/hepatitis G virus--virological response of HGV and pretreatment HGV viremia level.

BACKGROUND/AIMS: The response to interferon-alpha (IFN) therapy of recently isolated GB virus C and hepatitis G virus (HGV) is still unclear. To investigate the biochemical and virological response to IFN therapy in patients with chronic hepatitis C virus (HCV) infection concomitantly infected with HGV, 196 patients with HCV who had received IFN therapy were retrospectively studied. METHODS: HGV and HCV RNA were detected by reverse transcription nested polymerase chain reaction (RT-PCR). Serum HGV RNA levels were quantified by competitive RT-PCR. The HGV genotype was detected by restriction fragment length polymorphism analysis using the PCR products. RESULTS: Of 196 patients, 16 (8.2%) were positive for both HCV and HGV RNA before IFN therapy. There were no significant clinical and virological differences between the patients with dual infection and those with only HCV infection. During the therapy, a decrease or loss of serum HGV RNA level was observed in these patients. Six months after cessation of the therapy, five of 16 patients became negative for HGV RNA by RT-PCR. The pretreatment HGV RNA level of the patients who lost HGV RNA after cessation of IFN was low (median=10(3) copies/ml), compared to the level (median=10(7) copies/ml, p<0.01) in the patients with positive HGV RNA after the therapy. The HGV genotype of these 16 patients was the same type. CONCLUSIONS: These data suggest that: 1) there is no significant difference in response to IFN therapy between patients with dual and single infection; 2) HGV shows sensitivity to IFN therapy; and 3) in the patients who show a low pretreatment HGV RNA level, serum HGV RNA becomes undetectable by RT-PCR after cessation of IFN therapy.

Adult↗
PubMed1997

Induced expression of Thy-1 molecules on dermal endothelial cells in skin allografts.

We obtained evidence in a foregoing study that inducible Thy-1 on vascular endothelial cells functions as a possible vascular permeability modulator in the rat. We now report on the regulation and function of endothelial Thy-1 in skin allograft rejection in the rat. While no obvious expression of Thy-1 antigen on the vasculature can be seen in normal organs, dermal endothelial cells do express Thy-1 during allogeneic skin graft rejection and Freund's complete adjuvant (FCA)-induced inflammation. The antigen was weakly induced on tubular epithelial, but not on endothelial cells during kidney allograft rejection, and not in FCA-induced inflammation of the kidney. In contrast, Thy-1 antigen was not induced in the rejected lung or in FCA-induced inflammation of the lung. This pattern of Thy-1 regulation was transcriptionally regulated. Administration of anti-Thy-1 antibodies generated increased vascular permeability in skin allografts, although this procedure did not modulate survival of the grafts.

Animals↗
PubMed1997

Ageing reactions in a high carat gold alloy for dental porcelain bonding.

The phase transformation during continuous heating of a high carat gold alloy used for porcelain bonding was investigated by electrical resistivity measurements, hardness tests, X-ray diffraction and scanning and transmission electron microscopy. Four reaction stages (I, II, III and IV) were found. Stage I corresponded to the formation of a short-range order. A discontinuous precipitation took place in stage II, which contributed to remarkable hardening. Stages III and IV were reactions to the stable phases at each temperature region, and resulted in softening. The activation energies for stages I, II and III are 27.1, 33.8 and 58.2 kcal/mol, respectively.

Journal Article↗
PubMed1997

Cystic glucagonoma with loss of heterozygosity on chromosome 11 in multiple endocrine neoplasia type 1.

A 52-year-old man with a past history of a pituitary adenoma and hyperparathyroidism due to a parathyroid adenoma was admitted because of a solitary tumour of the pancreas revealed by ultrasonography. His family history was unremarkable. Plasma glucagon levels were slightly elevated (280 ng/l, normal range, 40-180 ng/l) with decreased plasma amino acid levels. Plasma glucagon levels disclosed an exaggerated response during an arginine infusion test and paradoxical elevation during a 75 g oral glucose tolerance test. Endoscopic ultrasonography revealed a monolocular cystic mass of about 3 cm in diameter in the body of the pancreas. A pancreatic tumour was diagnosed before surgery as a cystic glucagonoma. Intra-operative ultrasonography showed one cystic mass in the body of pancreas and two other solid tumours, about 1 cm and 0.5 cm in diameter, in the tail of the pancreas. Histologically, all three tumours showed neoplastic epithelial cells with round nuclei forming cords and/or a ribbon-like arrangement. They showed positive staining for Grimelius' silver stain and immunopositive cells for glucagon. Genetic analysis of the main cystic tumour revealed loss of heterozygosity (LOH) on chromosome 11. After the operation, the responses of plasma glucagon to arginine infusion and oral glucose became normal. Here we describe the usefulness of these provocation tests for early diagnosis and post-operative follow-up in a rare cystic glucagonoma associated with multiple endocrine neoplasia type 1 (MEN 1) which had LOH on chromosome 11.

Arginine↗
PubMed1997

Platelet-activating factor (PAF) and PAF acetylhydrolase activity in rat uterus and placenta during the late stages of pregnancy.

We evaluated the roles of platelet-activating factor (PAF) and PAF-acetylhydrolase (PAF-AH) activity in late pregnancy. Uterine and placental concentrations of PAF were determined by the washed rabbit platelet aggregation bioassay. Uterine, placental, and plasma PAF-AH activities were also assayed. PAF concentration in the uterus increased 4-fold between Days 15 and 21 of pregnancy. PAF was also determined in the placenta on Days 15 and 21. In contrast to findings in the uterus, the concentration in the placenta was decreased by 75%. Platelet aggregation caused by uterine and placental PAF was inhibited by the PAF receptor antagonists CV-3988 and TCV-309. Plasma and uterine PAF-AH activities decreased significantly between Days 15 and 21. In contrast, the placental PAF-AH activity significantly increased during this same time period. On the basis of these findings, it is suggested that the PAF concentration in the uterus and placenta may be regulated by intracellular PAF-AH and/or plasma PAF-AH activities. Increased PAF activity in the pregnant rat uterus may be related to the initiation of labor due to its known effect on myometrial contraction. Decreased PAF concentration in the placenta may contribute to the fetoplacental circulation due to its known hypotensive activity and the increase in vascular permeability.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1997

PRLTS gene alterations in human prostate cancer.

Since loss of heterozygosity on 8p22-p21.3 has been found frequently in prostate cancer, the status of a candidate tumor suppressor gene named PRLTS gene, recently cloned from the same region in some human malignancies, was examined in the present study. DNAs were isolated from 69 Japanese prostate cancer patients (37 localized and 32 cancer-death cases). Loss of heterozygosity at this gene locus was observed in 15 of 36 (42%) localized prostate cancer patients and 22 of 32 (69%) cancer-death patients. One cancer-death patient had a missense mutation, ACG-->ATG (Thr-->Met) at codon 64 in metastatic tumor tissues of pelvic lymph node and liver, and these tissues showed loss of the homologous allele, indicating that "two-hit" mutation of the PRLTS gene had occurred in this case. The others did not show any mutation, regardless of the presence or absence of loss of heterozygosity. Although loss of heterozygosity at the PRLTS gene locus is a relatively common abnormality, mutation of this gene is rare in prostate cancer.

Adenocarcinoma↗
PubMed1997

Morphogenesis and development of superficial spreading tumor of the colon and rectum.

The aim of this study was to clarify the morphogenesis and mechanism of a wide intramucosal extension of a superficial spreading (epithelial) tumor (SST; defined as an epithelial tumor with wide intramucosal spreading involving a diameter of 30 mm or more) in the colon and rectum. For this purpose favorable sites, histological components, and histological growth patterns were compared between 95 cases of SST (16 adenomas and 79 carcinomas) and 2356 non-SST cases, which served as controls. The frequency of SST was significantly higher in the cecum and rectum, and lower in the sigmoid colon when compared to the locations of the control. Among the SST cases, 82.3% of superficial spreading carcinoma (SSC) had an adenomatous component and 96.2% had a cytologically low-grade carcinoma (CAL). In intramucosal SSC, the adenomatous and/or CAL component was predominant, and the proportion of high-grade carcinoma (CAH) was significantly smaller in intramucosal SSC in comparison with the control group. In the mucosal spreading area of SST, 78.9% were tubulovillous in histological type and 86.3% showed a replacing growth pattern. These results indicate that an SST initially develops as an adenoma in at least 85.3% of cases and CAL in 14.7% cases at most; spreads superficially in the mucosa by a replacing growth mechanism that forms a tubulovillous and villous structure; and is affected by intestinal peristalsis less than non-SST.

Adenoma↗
PubMed1997

Effects of stimulated free latissimus dorsi muscle graft on LVEDV and LVSW: a new dynamic cardiomyoplasty technique.

The effectiveness of dynamic cardiomyoplasty (DCMP) remains controversial. We hypothesized that effectiveness of DCMP using the latissimus dorsi muscle graft (LDMG) depends on the wrapping method. We analyzed pressure-volume relations (PVR), the left ventricular stroke work (LVSW), and the left ventricular end diastolic volume (LVEDV) changes during nonstimulation and stimulation of the LDMG to evaluate the effect of a new wrapping method of DCMP on the LVSW and the LVEDV changes. The new wrapping technique was evaluated in an acute animal experimental model. In 12 mongrel dogs, we performed continuous measurement of the dimensional and pressure dates of the left ventricle (LV) after the DCMP. The measurement was performed 15 min after wrapping during 5 periods. The duration of one measurement period was 15 s. The animals were divided into 2 groups according to the wrapping method. The heart was wrapped with the LDMG using 2 different methods. For Method 1, Carpentier's method, the heart was wrapped primarily with the distal part of the LDMG, the lateral segment. The vasculoneural pedicle of the latissimus dorsi muscle (LDM) was preserved. For Method 2, the LDM was separated, and the vasculoneural pedicle was cut. The medical sternotomy was performed. The thoracodorsal artery of LDMG was anastomosed to the right internal mammary artery, and the thoracodorsal vein was anastomosed to the right atrial appendage. The heart was wrapped primarily with the proximal part of the "free LDMG," the transverse segment. Based on the PVR loops, the changes of the LVSW and the LVEDV in both experimental groups were analyzed. The paired t-test was used for statistical analysis. Using Method 1, the LVSW and the LVEDV showed no significant changes during stimulation (stim) of the LDMG, compared with nonstimulation (nonstim) (LVSW: nonstim, 970 +/- 168 erg x 10(3); stim, 1,181 +/- 203 erg x 10(3); p = 0.126 and LVEDV: nonstim, 36.6 +/- 6.7 ml; stim, 37.2 +/- 6.8 ml; p = 0.36). Using Method 2, the LVSW was increased, and the LVEDV was decreased during stimulation of the free LDMG, compared with nonstimulation (LVSW: nonstim, 694 +/- 117 erg x 10(3); stim, 846 +/- 104 erg x 10(3); p < 0.001 and LVEDV: nonstim, 47.7 +/- 2.8 ml; stim, 46.8 +/- 2.7 ml; p < 0.001). The stimulated free LDMG wrapping of the heart seems to be a more effective wrapping method for DCMP, and it results in an increase of the LVSW and a decrease of the LVEDV, compared with the original Carpentier's method.

Animals↗
PubMed1997

Using acoustic radiation force as a concentration method for erythrocytes.

We investigated the potential damage inflicted on erythrocytes by acoustic radiation force when the cells are concentrated by a 500-kHz ultrasonic standing wave at the pressure node. The extent of the damage was estimated from the concentrations of potassium ions, iron complexes, and lactate dehydrogenase released from the cells. After 2 min of ultrasound irradiation at 12.8 mJ/m3, the cells concentrated on the pressure node, with a cell distribution half-width of 138 microns; no significant release of intracellular components was detected, even after 15 min of irradiation. The results indicate that even small ions like potassium are not released as a result of ultrasound irradiation on cell membranes without cavitation, and they demonstrate the potential use of acoustic radiation force for concentrating living cells in biomedical applications.

Acoustics↗
PubMed1997

Micturitional disturbance in patients with Guillain-Barré syndrome.

OBJECTIVES: To examine the frequency and pathophysiology of micturitional disturbance in patients with Guillain-Barré syndrome. METHODS: Micturitional symptoms were noted and neurological examinations made repeatedly during admission to hospital of patients with clinical and neurophysiologically definite Guillain-Barré syndrome. Urodynamic studies consisted of uroflowmetry, measurement of residual urine, urethral pressure profilometry, medium fill water cystometry, and external sphincter EMG. RESULTS: Seven of 28 (25%) patients with Guillain-Barré syndrome showed micturitional disturbance. The symptoms included voiding difficulty in six, urinary retention in three, nocturnal urinary frequency in three, and urge incontinence in two. These micturitional symptoms appeared after weakness occurred, and improved gradually along with the neurological signs. All three patients who showed retention became able to urinate. Urodynamic studies were made on four symptomatic patients two of whom underwent repeated study. Disturbed bladder sensation was noted in one patient, bladder areflexia in one, and absence of the bulbocavernosus reflex in one. Cystometry showed decreased bladder volume in two and bladder overactivity in two, one of whom had urge urinary incontinence and the other urinary retention. CONCLUSIONS: A quarter of the patients with Guillain-Barré syndrome tend to have micturitional disturbance. The patients studied had evacuation and storage disorders, as well as bladder areflexia and disturbed bladder sensation indicative of peripheral types of parasympathetic and somatic nerve dysfunction. Decreased bladder volume with bladder overactivity but no evidence of CNS involvement was also found, evidence that bladder overactivity also occurs in peripheral nerve lesions with probable pelvic nerve irritation.

Adolescent↗
PubMed1997

Novel benzoxazole 2,4-thiazolidinediones as potent hypoglycemic agents. Synthesis and structure-activity relationships.

A new series of benzoxazole 2,4-thiazolidinediones was synthesized and evaluated for hypoglycemic activity in genetically obese and diabetic yellow KK mice. 2-Arylmethyl- and 2-(heteroarylmethyl)benzoxazole derivatives showed far more potent activity than known 2,4-thiazolidinedione derivatives such as ciglitazone, troglitazone and pioglitazone. A facile synthesis of benzoxazole 2,4-thiazolidinediones was also established using aminophenol 2,4-thiazolidinedione (11) as a key intermediate. Details of synthesis and structure-activity relationships for this series are described.

Animals↗
PubMed1997

Inflammatory abdominal aortic aneurysms and atherosclerotic abdominal aortic aneurysms--comparisons of clinical features and long-term results.

A total of 274 patients with abdominal aortic aneurysms due to atherosclerosis (AAA) and 16 patients with inflammatory abdominal aortic aneurysms (IAAA) were reviewed to compare and contrast the clinical characteristics of the 2 groups. The AAA group comprised 243 men and 31 women with a mean age of 69.2 +/- 0.4 (range 51-86) years. The IAAA group comprised 15 men and 1 woman with a mean age of 67.4 +/- 2.0 (range 53-81) years. Most patients with IAAA (12/16; 75.0%) had pain at presentation, whereas only 37 out of 274 patients (13.5%) with AAA had pain (p < 0.001). Fifty out of 274 patients (18.2%) with AAA were asymptomatic, the most common principal complaint being a pulsatile tumor, which was found in 150 out of 274 patients (54.7%; p < 0.005 vs IAAA). Regarding laboratory findings of inflammation, preoperative erythrocyte sedimentation rate values were elevated in 15 out of 16 (93.8%) patients, and C-reactive protein values were elevated in 13 out of 16 (81.3%) patients with IAAA. The incidence of perioperative complications was similar in the 2 groups. The 30-day postoperative mortality among AAA patients was 6.2% (17/274 cases), including 12 cases of non-ruptured and 5 cases of ruptured AAA; in contrast, no early deaths occurred among patients with IAAA. The cumulative 5-year survival rate was 80.2% for IAAA patients and 74.6% for AAA patients (NS). The results of our review suggest that careful diagnosis and intra- and postoperative management could lead to patients with IAAA having a similar survival rate to those with AAA.

Aged↗
PubMed1997

ACTH-induced cortisol secretion is mediated by cAMP and PKC in various adrenocortical adenomas.

We examined the role of PKC in cortisol secretion from adrenocortical adenomas. Isolated cells were prepared from aldosterone producing adenoma (APA, n=5), APA complicated with pre-clinical Cushing's syndrome (APA+PC, n=1), PC (n=2), and cortisol producing adenoma (CPA, n=5). They were stimulated with 100 nM ACTH, 1 microM forskolin (FS), 1 microM tetradecanoyl phorbol 13-acetate (TPA), and 100 nM angiotensin II (AngII). ACTH was most potent to secret cortisol. FS also stimulated cortisol secretion, but did less-potently. TPA and AngII also stimulated cortisol secretion significantly in cells from CPA. Furthermore, ACTH- and TPA-induced PKCalpha and beta translocations from cytosol to membrane were observed in adenoma cells from APA+PC, PC, and CPA. In conclusion, it was suggested that ACTH-induced cortisol secretion may be mediated by both PKC and protein kinase A in adrenocortical adenomas, and that PKC-mediated signal transduction may be involved in ACTH-induced cortisol secretion in CPA.

Adenoma↗
PubMed1997

[Electrophysiological and pharmacological properties of inhibitory postsynaptic potentials evoked in laryngeal motoneurons in decerebrate cats].

Electrophysiological and pharmacological properties of inhibitory postsynaptic potentials (IPSPs) induced in respiratory laryngeal motoneurons (LMNs) by electrical stimulation of the superior laryngeal nerve were investigated in decerebrate, paralyzed, vagotomized and artificially ventilated cats. In the inspiratory phase, a single pulse stimulation caused a short latency excitation followed by long-lasting inhibition of phrenic nerve discharge. A long latency wave of IPSPs occurred in inspiratory LMNs. In the expiratory phase, the same stimulation provoked a transient excitation in the phrenic nerve. An IPSP wave of long-latency was induced in post-inspiratory LMNs. The time course of each long-latency IPSP wave corresponded to that of either inspiratory inhibition or expiratory excitation of the phrenic discharge. These IPSP waves induced in both types of LMNs were decreased in amplitude by iontophoresed bicuculline but not by strychnine. These results suggest that laryngeally evoked IPSP waves in inspiratory and post-inspiratory LMNs are mediated through poly-synaptic pathways within the central respiratory network and that GABAA-receptors are involved in their final pathway.

Animals↗
PubMed1997

A coherent phase diagram of the [(AuCu)0.86Ag0.14]1-XPtX pseudobinary section in Au-Cu-Ag-Pt quaternary system.

In order to determine a coherent phase diagram of the [(AuCu)0.86Ag0.14]1-XPtX pseudobinary system, phase identifications and analyses of the microstructural configurations were performed by means of transmission electron microscopy. Various phase regions were detected in the coherent phase diagram as follows; (1) alpha 0 (fcc) single phase region, (2) two-phase region (alpha 1 + alpha 2), (3) AuCu I (L10) + alpha 0, (4) AuCu I + alpha 2, (5) AuCu II (L10-S) + alpha 2, (6) AuCu I + AuCu II + alpha 2, (7) AuCu I single phase region. Microstructural features of these regions relating to the phase transformations were described.

Chemical Phenomena↗
PubMed1997

Anisotropic expansion in gypsum-bonded cristobalite investment mold.

Expansion of a gypsum-bonded investment mold was investigated using a fused quartz tube pattern. Two hours after mixing, a fusible alloy was cast into the space around the pattern induced by setting expansion. The other molds were heated up to 700 degrees C, then a dental silver alloy was cast into the space around the pattern induced by total expansion of the mold. Thickness of the castings was measured at every thirty degrees on seven cross-sections. The setting expansion was almost uniform, but the total expansion was not. Especially, a large amount of total expansion was produced toward the open ends of the casting ring and toward a seam of the asbestos liner. The thermal expansion of the mold was anisotropic because the investment was a mixture of calcium sulfate and silica, and was affected considerably by its environment.

Anisotropy↗