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Biomedical subjects

S Imai

Publications and source records attributed to S Imai.

At least 91 records · Page 5Linked to original sources
PubMed1999

Detection of Epstein-Barr virus (EBV) in hepatocellular carcinoma tissue: a novel EBV latency characterized by the absence of EBV-encoded small RNA expression.

In this study, we investigated the presence of Epstein-Barr virus (EBV) in liver tissue from 35 patients with hepatocellular carcinoma (HCC). EBV DNA was detected in 13 patients (37%) by Southern blot hybridization. In 10 of these patients, EBV DNA was present in tumor tissue only, whereas in the other 3, it was detected in both tumor and nontumor tissues. The quantity of EBV DNA detected was equivalent to 1-10 viral DNA molecules/100 cells. EBV-determined nuclear antigen was detected in 7-13% of the carcinoma cells in three tumor tissue samples that contained approximately one copy of the EBV genome/10 cells. A single terminal fragment of EBV DNA was identified in these tissues, suggesting that the EBV-infected cells in HCC represent clonal proliferation. Western blotting and reverse transcription-polymerase chain reaction analyses demonstrated that these three tumor tissue specimens were positive for EBV-determined nuclear antigen 1 and BamHI A transcripts but were negative for the other latent EBV products, including EBV-encoded small RNA. The results indicated that there is a high EBV load in HCC tissue and that all of the HCC tissue examined showed a novel pattern of EBV latency characterized by absence of EBV-encoded small RNA expression.

Adult↗
PubMed1999

Reg1ulatory role and molecular interactions of a cell-surface heparan sulfate proteoglycan (N-syndecan) in hippocampal long-term potentiation.

The cellular mechanisms responsible for synaptic plasticity involve interactions between neurons and the extracellular matrix. Heparan sulfates (HSs) constitute a group of glycosaminoglycans that accumulate in the beta-amyloid deposits in Alzheimer's disease and influence the development of neuron-target contacts by interacting with other cell surface and matrix molecules. However, the contribution of HSs to brain function is unknown. We found that HSs play a crucial role in long-term potentiation (LTP), a finding that is consistent with the idea that converging molecular mechanisms are used in the development of neuron-target contacts and in activity-induced synaptic plasticity in adults. Enzymatic cleavage of HS by heparitinase as well as addition of soluble heparin-type carbohydrates prevented expression of LTP in response to 100 Hz/1 sec stimulation of Schaffer collaterals in rat hippocampal slices. A prominent carrier protein for the type of glycans implicated in LTP regulation in the adult hippocampus was identified as N-syndecan (syndecan-3), a transmembrane proteoglycan that was expressed at the processes of the CA1 pyramidal neurons in an activity-dependent manner. Addition of soluble N-syndecan into the CA1 dendritic area prevented tetanus-induced LTP. A major substrate of src-type kinases, cortactin (p80/85), and the tyrosine kinase fyn copurified with N-syndecan from hippocampus. Moreover, association of both cortactin and fyn to N-syndecan was rapidly increased after induction of LTP. N-syndecan may thus act as an important regulator in the activity-dependent modulation of neuronal connectivity by transmitting signals between extracellular heparin-binding factors and the fyn signaling pathway.

Animals↗
PubMed1999

Increased 9,13-di-cis-retinoic acid in rat hepatic fibrosis: implication for a potential link between retinoid loss and TGF-beta mediated fibrogenesis in vivo.

BACKGROUND/AIMS: During hepatic fibrosis, hepatic stellate cells (HSCs) transform into myofibroblastic cells and lose their intracellular droplets of retinyl esters, the storage form of vitamin A. Recently, we have demonstrated that 9,13-di-cis-retinoic acid (RA), a geometric isomer identified as a stable and major metabolite of vitamin A in circulation, stimulates the synthesis of plasminogen activator (PA) and induces PA/plasmin-dependent latent transforming growth factor (TGF)-beta activation in HSC cultures, probably via induction and activation of RA receptor (RAR) alpha. The aim of the present study was to address a potential link between the loss of retinyl esters to increased formation of RA(s), which might play a role in facilitating TGF-beta-mediated liver fibrogenesis in vivo. METHODS: We examined the effect of 9,13-di-cis-RA on transactivating activity of RARalpha in HeLa cells as well as its effect on PA- and TGF-beta-dependent collagen synthesis in rat and human HSC cultures. We measured the changes in 9,13-di-cis-RA levels both during activation of rat HSCs in vitro and during porcine serum-induced rat hepatic fibrosis in vivo and correlated this with RAR alpha/beta, PA, TGF-beta and type I procollagen mRNA expression in the fibrotic liver. RESULTS: 9,13-di-cis-RA transactivated RARalpha, and provoked PA/plasmin and TGF-beta-dependent procollagen synthesis in HSCs. 9,13-di-cis-RA levels were increased both in activated HSCs in vitro and in fibrotic liver accompanying the enhanced expression of RAR alpha/beta, PA, TGF-beta and procollagen in vivo. CONCLUSIONS: These findings suggest a potential link between 9,13-di-cis RA formation and hepatic fibrosis via formation of TGF-beta in vivo, and thus provide further insight into the biologic role of retinoids during hepatic fibrogenesis.

Animals↗
PubMed1999

IP3 production in A10 cells, an established aortic smooth muscle cultured cell line: effects of agonist administration procedure and culture conditions.

1. After normal culture (10% FBS), medium exchange itself evoked marked increases in IP3 levels in A10 cells that masked the net change in IP3 in response to vasopressin (100 nM). 2. Low-serum (0.3% FBS) culture for 10 days abolished the increase in IP3 by medium exchange, and increased expression of cGMP kinase. 3. Stimulation of cells with vasopressin (100 nM) by a pipetting procedure, increased IP3 levels irrespective of culture conditions. 4. This cell line therefore could be used in a contractile form (after low-serum culture) with pipetting procedure to observe IP3 response, especially with regard to interactions with the cGMP signaling system.

Animals↗
PubMed1999

Multi-institutional randomized clinical study on the comparative effects of intracavital chemotherapy alone versus immunotherapy alone versus immunochemotherapy for malignant effusion.

The current prospective randomized study was designed to compare the effects of intracavitary (i.c.) chemotherapy vs immunotherapy vs immunochemotherapy for malignant effusion. Between 1992 and 1995, a total of 42 patients with malignant effusion were registered, and 41 patients were eligible for statistical analysis. The primary diseases of the eligible patients included 27 gastric, four colorectal, four pancreatic, three lung, two liver and one oesophageal cancers. The patients with malignant effusion were randomly assigned into one of three i.c. therapeutic regimens: chemotherapy alone with weekly injection of anticancer agents (ACAs: cisplatin, mitomycin-C, adriamycin, etc.) (Group A, n = 13); immunotherapy alone with weekly injection of streptococcal preparation OK-432 (Group B, n = 14); or immunochemotherapy with ACAs and OK-432 (Group C, n = 14). The response of the effusion, patient survival and the kinetics of cytokines in the effusion were compared. There were no differences in the patients' backgrounds. The side-effects of the regimens included pain, anorexia, fever, leucopenia and anaemia and there were no differences in their incidence among the three groups. One patient died after cisplatin (CDDP) administration in Group A. Cytologic examination revealed that tumour cells in the effusion disappeared in 23% of Group A cases, 36% of Group B cases and 36% of Group C cases. The malignant effusion did not disappear in any of the Group A cases; however, the effusion disappeared in 29% of Group B cases and 43% of Group C cases (P = 0.03, Group A vs Group C). Furthermore, the 50% survival period was 1.6 months for Group A, 2.4 months for Group B and 3.5 months for Group C. The 6-month survival rate was 7% for Group A, 6% for Group B and 34% for Group C, and the 1-year survival rate was 0%, 0% and 17% respectively (P = 0.048, Group A vs Group C by the log-rank test). The analysis of the cytokine kinetics revealed a prominent increase in the level of interleukin-6 in the effusion in Group C. These results suggest that i.c. immunochemotherapy with OK-432 and ACAs may be more beneficial than i.c. chemotherapy alone or immunotherapy alone.

Adjuvants, Immunologic↗
PubMed1999

Epstein-Barr virus promotes epithelial cell growth in the absence of EBNA2 and LMP1 expression.

We attempted to infect primary gastric epithelia (PGE) with recombinant Epstein-Barr virus (EBV) carrying a selectable marker that made it possible to select EBV-infected cells. Cells dually positive for EBV-determined nuclear antigen (EBNA) and cytokeratin were detected in 3 of 21 primary cultures after 3 days of EBV inoculation. From one culture, EBV-infected cell clones were repeatedly obtained at a frequency of 3 to 5 cell clones per 10(6) cells. EBV-infected clones had enhanced population doubling and grew to attain a highly increased saturation density, together with acquisition of marked anchorage independence. The infected clones retained the ultrastructural morphology characteristic of gastric mucosal epithelium and have been growing stably for more than 18 months (corresponding to at least 300 generations) so far, in clear contrast to the parental PGE cells, which ceased growth after 60 generations. The p53 gene of the parental PGE cells was found to be overexpressed, perhaps thereby conferring the basal potential for long-term survival in vitro. Moreover, EBV infection accelerated, to a significant extent, the growth rate and agar clonability of NU-GC-3 cells, an established EBV-negative but EBV-susceptible human gastric carcinoma cell line. Both EBV-converted PGE and NU-GC-3 clones, like EBV-positive gastric carcinoma biopsy specimens, expressed a restricted set of EBV latent infection genes characterized by the absence of EBNA2 and latent membrane protein 1 (LMP1) expression. These results indicate that EBV infection causes a transformed phenotype on PGE in the setting of possible unregulated cell cycling and renders even established gastric carcinoma cells more malignant via a limited spectrum of viral latent-gene expression. This study may reflect an in vivo scenario illustrating multiphasic involvement of EBV in carcinogenesis of gastric or other epithelial cancers.

Cell Division↗
PubMed1999

Cytoplasmic liberation of protein gene product 9.5 during the seasonal regulation of spermatogenesis in the monkey (Macaca fuscata).

Primate spermatogenesis is distinguished by yet unidentified mechanisms to regulate its spermatogenetic activity. In contrast to the well documented hormonal regulators, the cellular events responsible for the regulation of the spermatogenesis has not been addressed. By using PGP 9.5-immunohistochemistry, our previous study demonstrated that the monkey spermatogonia are divided into two distinct sub-populations, i.e. cytoplasmic PGP 9.5-positive and cytoplasmic PGP 9.5-negative spermatogonia. By comparing the cytoplasmic expression of PGP 9.5 between the breeding and nonbreeding seasons of the Japanese monkey (Macaca fuscata) in association with PCNA labeling, the present study demonstrates that the cytoplasmic PGP 9.5-positive Ap spermatogonia significantly increases when the spermatogenetic activity declines in the nonbreeding season. An ultrastructural subcellular localization of PGP 9.5 suggests that the increase of the cytoplasmic PGP 9.5 expression is due to a liberation of PGP 9.5 molecule from the nucleus into the cytoplasm. The results provide a theoretical basis by which PGP 9.5 serves as a novel marker for spermatogonial subtypes, which will have further implications for future studies on spermatogenesis. The analysis using this novel marker suggests that the Ap spermatogonia is a key stage to regulate the amount of the sperm produced in response to the hormonal regulators, and the cytoplasmic liberation of PGP 9.5 may serve as a pivotal phenomenon that enables the fully restorable, transient suppression of spermatogenesis in primate.

Animals↗
PubMed1999

Rumen ciliate protozoal fauna of native sheep, friesian cattle and dromedary camel in Libya.

Rumen ciliate species and composition were surveyed on the native sheep, Friesian-cattle and dromedary (one-humped) camels kept in Libya. As a result of survey, 5 genera including 14 species with 5 formae in native sheep, 9 genera including 27 species with 6 formae in Friesian-cattle and 6 genera including 13 species and 7 formae in dromedary camels were identified. All of the ciliate species and their percentage composition detected from the Libyan sheep and cattle in this examination were similar to those found from corresponding animals in the other countries. Libyan camels lacked some peculiar ciliate species found from camels in the other countries, but had many cosmopolitan species common with those in the domestic ruminants, suggesting that ciliate faunae of camel are easily affected by the other domestic ruminants kept together. The ciliate density was estimated as 105/ml in every host species.

Animals↗
PubMed1999

Stimulation of plasma membrane Ca2+ -pump ATPase of vascular smooth muscle by cGMP-dependent protein kinase: functional reconstitution with purified proteins.

A 240-kDa protein isolated from porcine aortic smooth muscle as a substrate for cGMP-dependent protein kinase (cGMP kinase) whose phosphorylation was in a close association with stimulation of partially purified plasma membrane Ca2+ -pump ATPase by the kinase was later shown to represent splicing variants of type 1 inositol 1,4,5-trisphosphate (IP3) receptor. To further clarify the role played by this protein in the stimulation of Ca2+ -pumpATPase, it was attempted in thepresent study to specifically remove the protein by immunoprecipitation with an antibody specific to type 1 IP3 receptor. Contrary to expectation, stimulation of the ATPase by cGMP kinase was still observed after removal of the IP3 receptor. Furthermore, cGMP kinase stimulated a highly purified preparation of Ca2+ -pump ATPase deprived of IP3 receptor when the concentrations of the ATPase were low enough (10-20 nM) to make it retain a monomeric form, while it did not produce stimulation when the concentration of the enzyme was increased to 40 nM at which the enzyme is known to take an oligomeric, fully activated form insensitive to activation by calmodulin. Heat-inactivated cGMP kinase and cGMP kinase without cGMP failed to stimulate the highly purified Ca2+ -pumpATPase. In addition, type Ialpha but not type Ibeta cGMP kinase was found to stimulate the ATPase. The stimulation of Ca2+ -pump ATPase by cGMP kinase occurs without any detectable phosphorylation of the ATPase. In conclusion, cGMP kinase can stimulate the plasma membrane Ca2+ -pump ATPase when it is in a monomeric form without phosphorylating the Ca2+ -pump ATPase and that of the two cGMP kinase isozymes found in the vascular smooth muscle, only type Ialpha cGMP kinase participates in the stimulation.

Animals↗
PubMed1999

[High inducibility of Epstein-Barr virus replication in B lymphocytes in Vogt-Koyanagi-Harada disease].

PURPOSE: The role of Epstein-Barr virus (EBV) reactivation in the pathogenesis of Vogt-Koyanagi-Harada (VKH) disease was examined. MATERIAL AND METHODS: Using B lymphocytes obtained from 8 patients with VKH disease and 10 patients with other types of uveitis, immortarized lymphoblast lines were established and infected with EBV. The degree of EBV activation in each lymphoblast line, in the presence and absence of various stimuli, was assessed by measuring the expression of 3 different antigens involved in replication by immunofluorescent staining and western blot analysis. Quantification of EBV DNA in cell culture supernatants was done by polymerase chain reaction. RESULT: Cell lines established from VKH patients expressed more viral antigens that those established from patients with other types of uveitis. There were greater amounts of EBV DNA in the VKH cell lines. CONCLUSION: B lymphocytes from VKH patients may be more susceptible to EBV activation, and the reactivation of EBV may be involved in the pathogenesis of VKH.

Adult↗
PubMed1999

Bone augmentation by recombinant human BMP-2 and collagen on adult rat parietal bone.

A composite of recombinant human bone morphogenetic protein-2 (rhBMP-2) and collagen was implanted beneath the cranial periosteum of 10-month-old rats to observe bone development and absorbent change of carrier collagen. The rhBMP-2/collagen onlay implant resulted in active bone formation and the augmented bone was connected directly with the original bone, whereas the collagen alone resulted in neither bone nor cartilage. The ossification process in the rhBMP-2/collagen occurred directly through bone formation, similar to intramembranous ossification. The carrier collagen fibers were found in the woven bone and were completely absorbed at 8 weeks in the presence of rhBMP-2, while the collagen alone implant remained encapsulated by a thin, fibrous connective tissue. Our results indicate that rhBMP-2/collagen is an effective material as a biological onlay implant, showing osteoinductive properties and being completely replaced by new bone. Carrier collagen not only plays a role in rhBMP-2 delivery, but also provides a cell anchorage for cell differentiation and remains as an artificial matrix in woven bone.

Absorbable Implants↗
PubMed1999

[Usefulness of percutaneous sclerosing treatment for low-flow vascular lesions].

Peripheral vascular lesions may occur as a result of various clinical problems, cosmetic or dysfunctional causes, or bleeding. In severe cases, coagulopathy and congestive heart failure may occur. Although the efficacy of transarterial embolization (TAE) for arterial vascular lesions is well known, TAE has no effect on low-flow vascular lesions (venous malformations, venous angiomas, and venous components of arteriovenous malformation). Therefore, in such cases, a percutaneous approach is the best method, and we consider sclerotherapy to be the most useful conservative treatment. The primary objective of this study was to confirm the efficacy of percutaneous sclerosing treatment for peripheral low-flow vascular lesions. Lesions were classified on the basis of state of blood flow and morphologic features, and infiltration was classified on the basis of angiographic features and magnetic resonance imaging (MRI) findings. In sclerosing treatment, we used 5% solutions of polidocanol, absolute ethanol, and N-butyl-2-cyanoacrylate (NBCA) as sclerosing agents. Each type of lesion, static or slow-flow, cystic, or localized, showed remarkable improvement after sclerosing treatment with only polidocanol. However, for moderate-to-fast-flow lesions, another sclerosing agent (absolute ethanol/NBCA) was needed. With diffuse infiltrative lesions, surgical repair might be needed, but we recognize the usefulness of sclerosing treatment for functional or cosmetic improvement in these cases.

Adolescent↗
PubMed1999

[Comparative study of histopathological effects of preoperative chemotherapy using UFT and in vitro MTT assay of colonoscopy specimens from patients with colorectal cancer].

In previous studies, we demonstrated that the histopathological effects of 5-FU on colorectal cancer corresponded with the clinical effects. We measured the chemosensitivity of colorectal cancer to 5-FU by MTT assay using specimens from colonoscopy, and compared this with the histopathological effects. Forty-five patients with histologically proven colorectal cancer were enlisted for this study. Patients first underwent colonoscopy, and MTT assays were performed. Afterwards, preoperative UFT chemotherapy at a dose of 600 mg/day was given over 10 days before the operation. The histopathological effects of the resected tumors in response to 5-FU were estimated. Seven of 37 patients were judged sensitive to 5-FU by MTT assay. The response rate was 18.9%. On the other hand, 30 of 37 were evaluated as insensitive. Five of 7 patients with sensitivity to 5-FU were also evaluated as sensitive according to the histopathological effects. The sensitivity true positive rate was 71.4%. Twenty-nine patients without sensitivity to 5-FU were also evaluated as insensitive according to the histopathological effects. The specificity true negative rate was 96.7%, and the accuracy rate was 91.9%. The chemosensitivity of colorectal cancer to 5-FU, determined by MTT assay, was nearly consistent with the histopathological effects, so it may also be expected to correspond with the clinical effects.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

[Atresia of the right atrial orifice of the coronary sinus with persistent left superior vena cava: a case report].

A 39-year-old woman presented with atresia of the right atrial orifice of the coronary sinus with a persistent left superior vena cava detected at cardiac catheterization. She was admitted with frequent episodes of angina at rest and on exertion. Coronary angiography, including spasm provocation test, yielded normal results. However, left coronary arteriography demonstrated a dilated coronary sinus and a persistent left superior vena cava draining into the innominate vein. The contrast medium leaked slightly into the right atrial cavity through the obstructed orifice of the coronary sinus. Atresia of the coronary sinus orifice is a rare malformation usually found at autopsy. Only 3 cases have been reported in Japan. This is the first adult Japanese case detected when the patient was still alive.

Adult↗
PubMed1999

Sodium/hydrogen ion exchange inhibitor ameliorates ischaemia-reperfusion injuries in the rat hind limb.

PURPOSE: This study was designed to investigate the effect of a newly synthesised sodium/hydrogen ion exchange inhibitor, SM-20550, on ischaemia-reperfusion induced injury in a rat hind limb model. METHODS: In order to induce ischaemia of the hind limbs, the abdominal aorta just distal to the renal arteries and the bilateral femoral arteries were clamped. Nineteen rats were divided into three groups. In the sham group (n=5), the vessels were only dissected and a vehicle solution was administered. In the control group (n=7), the vessels were clamped for five hours, and a vehicle solution was administered 10 minutes prior to clamping and continued for five hours after reperfusion. In the SM group (n=7), clamping was maintained for five hours with a bolus injection of SM-20550 and continuous infusion of the solution for five hours after reperfusion. Water content of the left gastrocnemius muscle was calculated. The right gastrocnemius was fixed in 10% formalin. A transverse thin section was stained with antimyoglobin antibody. Stained cells of the right gastrocnemius were counted and the myoglobin staining index was calculated. RESULTS: Water content was significantly (p<0.002) lower in the SM group than in the control group. The myoglobin staining index was significantly (p<0.01) higher in the SM group than in the control group. There was no significant difference between the control and the SM groups in creatinine phosphokinase (CPK) and lactate dehydrogenase (LDH). CONCLUSIONS: Our results indicate that the sodium/hydrogen ion exchange inhibitor, SM-20550, ameliorates oedema formation and ischaemia-reperfusion induced injury of the skeletal muscle.

Amidines↗
PubMed1999

Influence of retinyl acetate on osteochondral junction chondrocytes in C3H and balb mice.

OBJECTIVE: To establish the pathophysiology of retinoid induced hyperostosis. METHODS: Radiographical, histological, ultrastructural, and immunohistochemical features of retinoid induced hyperostosis were evaluated using C3H-Heston mice and Balb mice. RESULTS: Dose dependent and progressive ossification was noted at extraosseous sites of both mouse strains. New bone formation was seen not only in the extraosseous tissues, but subchondral bone showed prominent proliferation. Major histopathological abnormalities appeared to take place in the chondrocytes near the osteochondral junctions, and some of the metaplastic chondrocytes near the osteochondral junction expressed osteocalcin and type I collagen, extracellular molecules normally present in bone. Species dependent responsiveness was also noted. CONCLUSION: Longterm administration of retinoids may induce an aberrant differentiation of the articular and entheseal chondrocytes near the osteochondral junctions, and the affected cells appeared to produce extracellular components including osteocalcin and type I collagen.

Animals↗