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Biomedical subjects

Y Shimada

Publications and source records attributed to Y Shimada.

At least 145 records · Page 8Linked to original sources
PubMed2000

Curative resection of microgastrinomas based on the intraoperative secretin test.

The intravenous secretin injection test (secretin test) has been used for the differential diagnosis of gastrinoma. In this study we report that the intraoperative secretin test (IOS test) is also useful for determining the extent of curability in patients with Zollinger-Ellison syndrome (ZES). Twelve patients with ZES underwent surgical exploration and the IOS test. The results of the IOS test were obtained by rapid radioimmunoassay of the serum gastrin level (IRG) within 60 minutes. The test was diagnosed as negative when the maximum increase of serum IRG was less than 80 pg/ml and also less than 20% of the basal serum IRG level. Three of the twelve patients underwent pancreatoduodenectomy (PD), and two patients underwent distal pancreatectomy. Extirpation of duodenal tumors with dissection of regional lymph nodes was performed in seven patients. In two of the seven patients the IOS test remained positive after extirpation of the duodenal tumors and the dissection of regional lymph nodes. In one patient PD was performed on the basis of the positive results, and the IOS test became negative after PD. In the other patient, two tiny metastatic liver tumors were identified and were resected, but the IOS test did not become negative. We closed the abdomen in 11 patients when we obtained negative results from the IOS test. The results of the IOS test were almost identical to the data obtained by the standard assay postoperatively. The serum IRG levels of all but one patient fell to the normal level, and the secretin test became negative postoperatively. The IOS test is thus useful and indispensable for curative resection of microgastrinomas in patients with ZES.

Adult↗
PubMed2000

Slow recovery of goldfish retinal ganglion cells' soma size during regeneration.

The goldfish optic nerve regenerates after sectioning. Recently both short-term (30 days) and long-term (4 months) recovery of various goldfish behaviors were observed after optic nerve section. Using intracellular injection of Lucifer Yellow (LY) the morphology of regenerating ganglion cells in goldfish retina after optic nerve section over a 4 month period have been investigated. In normal retinas, most cells (96-98%) were 7-10 microm in soma diameter which increased with increasing distance from the optic disc. Only two or three short, thin processes could be traced with LY. The remaining cells (2-4%) were 13-16 microm in soma diameter and all of the long dendritic trees could be traced with LY. The most conspicuous morphological change observed was cellular hypertrophy, which occurred for 20-90 days after axotomy. Neuronal processes were also hypertrophic in this period. The percentage increase in hypertrophy of the central ganglion cells tended to be slightly higher compared to cells from other regions. These morphological changes peaked at 60 days after axotomy and fully disappeared by 120 days after axotomy. The slow recovery of ganglion cells' soma size may reflect the slow return to the normal number of optic axon terminals in the tectum during regeneration.

Animals↗
PubMed2000

Histological response of cisplatin predicts patients' survival in oesophageal cancer and p53 protein accumulation in pretreatment biopsy is associated with cisplatin sensitivity.

The aim of this study was to evaluate whether cisplatin sensitivity relates to patient's prognosis in oesophageal squamous cell carcinoma and to find a useful chemosensitivity molecular marker. 59 oesophageal squamous cell carcinoma (SCC) patients received cisplatin 30 mg/m2/week treatment of two to five cycles, followed by oesophagectomy. We analysed retrospectively whether the histological effect was related to patient's prognosis. Furthermore, to evaluate the relationship between the effect of preoperative cisplatin treatment and p53 and cyclin D1 expression, we investigated p53 and cyclin D1 expression in pretreatment biopsy samples using an immunohistochemical analysis and compared the results with the histological effect to cisplatin in the resected oesophagus. The cases that showed immunohistochemical p53 staining in the pretreatment biopsy samples were resistant to cisplatin (P = 0.032). However, there was no relationship between cyclin D1 expression and histological effect (P = 0.230). Nevertheless, combined analysis of p53 and cyclin D1 can predict histological effect (P = 0.032). The prognosis of cisplatin-sensitive cases was significantly better than that of cisplatin-resistant cases (P = 0.041). Cox's multivariate analysis revealed that the histological effect was an independent prognostic factor. In contrast, p53 protein accumulation and cyclin D1 were not. Histological response after neoadjuvant cisplatin treatment is a prognostic factor for oesophageal SCC and cisplatin chemotherapy may be selected according to the findings of p53 and cyclin D1 expression.

Antineoplastic Agents↗
PubMed2000

Evaluation of tracheo-bronchial wall invasion using transbronchial ultrasonography (TBUS).

BACKGROUND: Whereas accurate evaluation of tumor invasion into the tracheo-bronchial wall is a critical factor in decision-making of therapy for intra-thoracic malignancies, it is sometimes difficult with usual thoracic imaging techniques such as computed tomography. As recent progress in technology of ultrasonography is marked, usefulness of transbronchial ultrasonography (TBUS) in evaluation of tracheo-bronchial wall invasion was assessed. METHODS: Following routine fiberoptic bronchoscopy, an ultrasound probe (20 MHz) covered with a balloon sheath was inserted through the bronchoscope. After air present between the ultrasound probe and the tracheo-bronchial wall was eliminated with filling the balloon with distilled water, TBUS imaging was taken. RESULTS: With TBUS, normal tracheo-bronchial wall was represented as a five-layer structure at the cartilagenous portion and a three-layer structure at the membranous portion. Based on this normal TBUS imaging, tumor extent was judged in 35 patients with intra-thoracic malignancies. Among 25 patients with extra-wall tumor including esophageal cancer (n=15) and metastatic lymph nodes (n=7), tracheo-bronchial wall invasion was clearly demonstrated in nine patients, and no invasion was demonstrated in the other 16 patients. Among ten patients with tumor originating from the tracheo-bronchial wall, tumor extent beyond outer border of the wall was demonstrated with TBUS in five patients. These diagnoses were examined pathologically in 15 patients who underwent the operation, and the accuracy was 93.3%. CONCLUSIONS: It is suggested TBUS can be a useful diagnostic tool in evaluation of tumor invasion to the tracheo-bronchial wall.

Adult↗
PubMed2000

Phosphorylation of the Cdc42 exchange factor Cdc24 by the PAK-like kinase Cla4 may regulate polarized growth in yeast.

Rho-type GTPases control many cytoskeletal rearrangements, but their regulation remains poorly understood. Here, we show that in S. cerevisiae, activation of the CDK Cdc28-Cln2 at bud emergence triggers relocalization of Cdc24, the GEF for Cdc42, from the nucleus to the polarization site, where it is stably maintained by binding to the adaptor Bem1. Locally activated Cdc42 then polarizes the cytoskeleton in a manner dependent on its effectors Bni1 and the PAK-like kinase Cla4. In addition, Cla4 induces phosphorylation of Cdc24, leading to its dissociation from Bem1 at bud tips, thereby ending polarized bud growth in vivo. Our results thus suggest a dynamic temporal and spatial regulation of the Cdc42 module: Cdc28-Cln triggers actin polarization by activating Cdc42, which in turn restricts its own activation via a negative feedback loop acting on its GEF Cdc24.

Actins↗
PubMed2000

Amino acid residues contributing to stabilization of Fusarium heterosporum lipase.

Fusarium heterosporum lipase is composed of an N-terminal large peptide of 275 amino acids and a C-terminal peptide of 26 amino acids. The thermostability of the lipase was remarkably decreased by cleavage of the C-terminal peptide. Hence, we attempted to specify the amino acids in the C-terminal peptide that are responsible for the stabilization of the lipase. Replacement of Asp293 with Ala, Asn, and Lys caused a significant decrease in thermostability, but its mutation to Glu did not decrease the stability significantly. These findings showed that the lipase with the C-terminal peptide was stabilized by an ionic bond between the negative charge of Asp293 and positive charge of an amino acid of the N-terminal large peptide. The thermostability of the lipase gradually decreased with increasing deletion size from the C-terminus, and a 13-amino acid deletion decreased the stability to the level of the lipase not having the C-terminal peptide. These results suggested that the 13-amino acid region from the C-terminus participated in the lipase stability. In addition, the lipase production correlated well with the lipase stability, showing that the C-terminal peptide also influenced the lipase productivity.

Journal Article↗
PubMed2000

Distribution of oscillatory components in the central retina.

This study examines the characteristics and the naso-temporal asymmetries of the higher-order oscillatory components of the multifocal electroretinogram (mERG). The magnitude of the mERG asymmetry and the mechanisms which produce it have not been studied previously. We recorded the mERG from seven normal observers using slow multifocal flicker and response filtering of 10-300 Hz. This permitted, without additional filtering, examination of the dominant first order component and the oscillation-rich components in the first and second order kernels. The oscillatory components in the two kernels had multiple peaks separated by about 6.8 ms, similar to those of conventional oscillatory potentials. Naso-temporal asymmetry of the three response components was analyzed in three groups (concentric rings around the fovea) spanning 1.5-10 deg of retinal eccentricity. The oscillation-rich components were, on average, approximately 14% larger in amplitude in the temporal retina than in corresponding nasal locations (p < 0.05) while the dominant first order component was not asymmetrically distributed. We tested the hypothesis that the asymmetry could be modeled as a combination of a retinal component (RC) and an optic nerve head component (ONHC) which varies in latency as a function of distance from the optic disc. We found that both oscillatory components and the dominant first order response could be decomposed into RCs and ONHCs that are symmetrically distributed. Thus, it appears that the naso-temporal asymmetries of the oscillation-rich components are produced primarily by the relative alignment and enhancement of RC and ONHC wavelets in the temporal retina, and misalignment and partial cancellation in the nasal retina.

Adult↗
PubMed2000

Dynamics of actin and alpha-actinin in nascent myofibrils and stress fibers.

Actin labeled with fluorescein isothiocyanate (FITC) and alpha-actinin labeled with rhodamine (rh) were co-injected into chick embryonic cardiac myocytes and fibroblasts. In cardiomyocytes, FITC-actin was distributed in nonstriated lines, linearly arranged punctate structures with short intervals, and cross-striated bands with regular sarcomeric intervals. rh-alpha-Actinin was seen to be distributed in the same pattern in the former two portions, and in the center of each striation in the latter portion. Photobleaching of structures incorporated with these fluorescent analogs revealed that the fluorescent recovery rate of actin decreased in the order of nonstriated > punctated > striated portions, while that of alpha-actinin was low and stable at all portions. During the transition phase from punctate to regular sarcomere structures of these proteins, short spaced alpha-actinin dots adjoined each other and aligned with Z bands of neighboring myofibrils. It appears that both the difference in exchangeability between actin and alpha-actinin molecules and the movement of alpha-actinin dots during this phase of myofibrillogenesis are related to sarcomere lengthening and I-Z-I brush formation; adjoining dots of low-exchangeable alpha-actinin may provide favorable situations for exchangeable actin molecules in filaments to elongate and/or rearrange. In fibroblasts, both FITC-actin and rh-alpha-actinin formed nonstriated lines. In these cells, exchangeabilities of both proteins were high and similar in rate. This seems to indicate that stress fibers are constantly exchanging their components for motile and other vital functions of these cells. The high exchangeabilities of both proteins in stress fibers showthat these fibers are clearly different from nonstriated, stress-fiber like structures of nascent myofibrils.

Actinin↗
PubMed2000

Nuclear sequestration of the exchange factor Cdc24 by Far1 regulates cell polarity during yeast mating.

Cytoskeletal rearrangements during the cell cycle and in response to signals are regulated by small Rho-type GTPases, but it is not known how these GTPases are activated in a spatial and temporal manner. Here we show that Cdc24, the guanine-nucleotide exchange factor for the yeast GTPase Cdc42, is sequestered in the cell nucleus by Far1. Export of Cdc24 to a site of cell polarization is mediated by two mechanisms. At bud emergence, activation of the G1 cyclin-dependent kinase Cdc28-Cln triggers degradation of Far1 and, as a result, relocation of Cdc24 to the cytoplasm. Cells overexpressing a non-degradable Far1 were unable to polarize their actin cytoskeleton because they failed to relocate Cdc24 to the incipient bud site. In contrast, in response to mating pheromones, the Far1-Cdc24 complex is exported from the nucleus by Msn5. This mechanism ensures that Cdc24 is targeted to the site of receptor-associated heterotrimeric G-protein activation at the plasma membrane, thereby allowing polarization of the actin cytoskeleton along the morphogenetic gradient of pheromone. Either degradation of Far1 or its nuclear export by Msn5 was sufficient for cell growth, suggesting that the two mechanisms are redundant for cell viability. Taken together, our results indicate that Far1 functions as a nuclear anchor for Cdc24. This sequestration regulates cell polarity in response to pheromones by restricting activation of Cdc42 to the site of pheromone receptor activation.

Biological Transport↗
PubMed2000

Total spondylectomy for primary tumor of the thoracolumbar spine.

STUDY DESIGN: Six patients with primary malignant tumor of the thoracolumbar spine who underwent total spondylectomy (TS) by en bloc resection were reviewed retrospectively. OBJECTIVES: To report surgical technique and preliminary results of TS and to evaluate its oncological curability. SETTING: Japan. METHODS: Six patients were treated by TS by en bloc resection of the vertebral tumor. TS through a posterior approach was performed in three cases (T1 osteosarcoma, L1 osteosarcoma and L1 chordoma) and in the others through a single stage anterior and posterior combined approach (T6-8 recurrent giant cell tumor. L4 chordoma and L5 giant cell tumor). Surgical margins of the specimens were evaluated histologically. All patients were followed, and their status was evaluated by clinical and imaging studies. RESULTS: There were no complications related to surgery. Programmed sacrifice of nerve roots were performed in three cases for oncologic excision. A wide surgical margin was achieved in one case, a marginal one in four, and an intralesional margin in one. Five patients were alive without evidence of tumor and one was alive with disease at follow-up evaluation after 2.0-4.8 years. Local recurrence was found in one case of T1 osteosarcoma with an intralesional margin. CONCLUSIONS: These preliminary results suggested that TS is an effective procedure in control of local recurrence with acceptable complications.

Adolescent↗
PubMed2000

Total en-bloc spondylectomy for correcting congenital kyphosis.

STUDY DESIGN: A case report of congenital kyphosis corrected using a total en-bloc spondylectomy. OBJECTIVES: To report a new surgical technique for the treatment of congenital kyphosis with myelopathy. SETTING: Department of Orthopedic Surgery, Akita University School of Medicine, Akita, Japan. METHODS: A 16-year-old boy who showed a 61 degrees angular kyphosis and a 32 degrees scoliosis from T6 to T9 due to the failure of the vertebral bodies formation in T7 and T8 was treated with a total en-bloc spondylectomy. RESULTS: The kyphosis was corrected to 26 degrees (57.3%) and the scoliosis was corrected to 5 degrees (84.4%) postoperatively. Three years postoperatively, no loss of correction has occurred and the patient has no complaints. CONCLUSIONS: Total en-bloc spondylectomy is one of the useful surgical procedures for correction of congenital kyphosis Type I, with a high correction rate. Spinal Cord (2000) 38, 382 - 385.

Adolescent↗
PubMed2000

Decreased expression levels of L-selectin on subsets of leucocytes and increased serum L-selectin in severe psoriasis.

L-selectin is a leucocyte adhesion molecule involved in leucocyte interactions with vascular endothelial cells. Following leucocyte activation L-selectin is endoproteolytically released from the cell surface. To assess whether psoriasis vulgaris results in systemic leucocyte activation, we examined expression levels of L-selectin on subsets of peripheral blood leucocytes from patients with psoriasis (n = 25) and normal control subjects. Serum levels of soluble L-selectin were quantified by ELISA in patients with psoriasis (n = 75), pustulosis palmaris et plantaris, and contact dermatitis, as well as normal control subjects. Psoriasis severity was evaluated by psoriasis area and severity index (PASI). L-selectin expression levels on CD4+ T cells, B cells, monocytes, and neutrophils from patients with severe-type psoriasis (PASI > or = 15) was significantly decreased compared with leucocytes from normal control subjects. Furthermore, L-selectin expression on CD4+ T cells showed good inverse correlation with PASI scores. Monocyte L-selectin expression was restored when the skin lesions of psoriasis were remitted. The frequencies of L-selectin+ CD4+ T cells or L-selectin+ CD8+ T cells from patients with psoriasis were almost normal. Serum L-selectin levels in patients with severe-type psoriasis were significantly higher than those in normal control subjects. These results suggest that subsets of leucocytes may be activated in psoriasis, and that L-selectin expression levels on some leucocyte subsets, especially CD4+ T cells, tend to correlate with disease severity of psoriasis.

Adult↗
PubMed2000

The absence of ribonuclease H1 or H2 alters the sensitivity of Saccharomyces cerevisiae to hydroxyurea, caffeine and ethyl methanesulphonate: implications for roles of RNases H in DNA replication and repair.

BACKGROUND: RNA of RNA-DNA hybrids can be degraded by ribonucleases H present in all organisms including the eukaryote Saccharomyces cerevisiae. Determination of the number and roles of the RNases H in eukaryotes is quite feasible in S. cerevisiae. RESULTS: Two S. cerevisiae RNases H, related to Escherichia coli RNase HI and HII, are not required for growth under normal conditions, yet, compared with wild-type cells, a double-deletion strain has an increased sensitivity to hydroxyurea (HU) and is hypersensitive to caffeine and ethyl methanesulphonate (EMS). In the absence of RNase H1, RNase H2 activity increases, and cells are sensitive to EMS but not HU and are more tolerant of caffeine; the latter requires RNase H2 activity. Cells missing only RNase H2 exhibit increased sensitive to HU and EMS but not caffeine CONCLUSIONS: Mutant phenotypes infer that some RNA-DNA hybrids are recognized by both RNases H1 and H2, while other hybrids appear to be recognized only by RNase H2. Undegraded RNA-DNA hybrids have an effect when DNA synthesis is impaired, DNA damage occurs or the cell cycle is perturbed by exposure to caffeine suggesting a role in DNA replication/repair that can be either beneficial or detrimental to cell viability.

Caffeine↗
PubMed2000

Detection of lymph node metastasis of oesophageal cancer by RT-nested PCR for SCC antigen gene mRNA.

With recent development in molecular biology, reverse transcriptase polymerase chain reaction (RT-PCR) has been applied to detect occult lymph node metastasis, but there have been few reports concerning oesophageal cancer. The objective of this study is to investigate the usefulness of the squamous cell carcinoma (SCC) antigen gene as a marker with RT-nested PCR to detect occult lymph node metastases of oesophageal cancer. The SCC antigen has been widely used as a serum tumour marker and was reported as a target gene to detect tumour cells in peripheral blood in cervical cancer. In this study, 620 lymph nodes from 14 oesophageal cancer patients were analysed. The results of RT-nested PCR were compared with that of pathological and immunohistochemical examinations. In the test of sensitivity, the RT-nested PCR detected 10(1) of SCC antigen producing cells in 10(7) peripheral blood mononucleocytes and was not found in 43 control lymph nodes. The pathological examination, immunohistochemical examination and the RT-nested PCR detected 36, 45 and 65 nodes respectively. The RT-nested PCR detected statistically more lymph nodes than the pathological or immunohistochemical examination. The sensitivity and specificity seem higher in squamous cell carcinoma cases. The SCC antigen gene is one of the more useful markers for RT-nested PCR to detect occult lymph node metastases of oesophageal cancer.

Antigens, Neoplasm↗
PubMed2000

Inhibition of nebulin and connectin (titin) for assembly of actin filaments during myofibrillogenesis.

In order to examine the role of cytoskeletal scaffolding proteins, nebulin and connectin (titin), in actin dynamics during myofibrillogenesis, rhodamine (rh)-labeled actin was microinjected into cultured skeletal muscle cells in which the function of these proteins had been inhibited with their respective antibodies. In the nebulin function-inhibited cells, exogenously introduced actin formed irregularly distributed amorphous patches or bright foci inside the cells, but it was not incorporated into myofibrillar structures at any stage. Thus, the blockage of actin binding sites of nebulin seems to inhibit the association of actin monomers to the preexisting nebulin scaffold. In the cells inhibited with anti-connectin antibody, incorporation of rh-actin was similar to that in antibody-uninjected cells. These results support the idea that nebulin is related to the accessibility/exchangeability of actin into nascent myofibrils, but connectin does not have such a role in actin assembly. Since all antibodies recognizing different domains of nebulin filaments blocked actin incorporation along the entire length of actin filaments, inhibition of any domains of nebulin filaments seems to affect actin dynamics.

Actin Cytoskeleton↗
PubMed2000

Measurement of the adhesive force of fine particles on tablet surfaces and method of their removal.

The adhesion force of fine particles on the surface of tablets was measured by a centrifugal force and impact separation method. A Finededuster (FDD) was employed to remove fine particles from the tablet surface. The centrifugal force and impact separation method was suggested to be effective for measuring the adhesive forces between particles and the tablet surface, and effective disjoining force in the FDD could be estimated by comparison of the results obtained using these two methods. The FDD showed high removal efficiency regardless of how many tablets were processed at the same time. In either of these methods, critical particle size was about 10-20 microns, and larger particles were removed more efficiently. This critical particle size was similar to that observed for other mechanical properties of powders, such as angle of repose and flowability. We simulated particle residual percentage under various operation conditions by ANN (artificial neural network) analysis and multiple regression analysis. This simulation enabled us to predict how the efficiency of particle removal is affected by the interaction of the experimental and material factors.

Administration, Oral↗