TPA-induced cohort migration of well-differentiated human rectal adenocarcinoma cells: cells move in a RGD-dependent manner on fibronectin produced by cells, and phosphorylation of E-cadherin/catenin complex is induced independently of cell-extracellular matrix interactions

We have already presented a two-dimensional cell motility assay using a highly metastatic variant (L-10) of human rectal adenocarcinoma cell line RCM-1 as a motility model of tumour cells of epithelial origin. In this model, L-10 cells showed locomotion as a coherent sheet when stimulated with 12-O-tetradecanoylphorbol-13-acetate (TPA), and we called this type of movement "cohort migration". Electron and immunoelectron microscopic study of the migrating cell sheets demonstrated localized release from cell-cell adhesion only at the lower portion of the cells with loss of E-cadherin immunoreactivity, and this change was associated with increased tyrosine phosphorylation of the E-cadherin-catenin complex, including beta-catenin. Cell-extracellular matrix (ECM) interactions involved in this TPA-induced cohort migration and their effect on tyrosine phosphorylation of the E-cadherin-catenin complex have now been investigated. L-10 cell cohort migration was almost completely inhibited by addition of Arg-Gly-Asp (RGD) peptide into the medium, and thus RGD dependent. Cohort migration was stimulated on type I and IV collagens, fibronectin (FN)- and laminin-coated substratum, but was inhibited by RGD only on FN-coated surface. By using immunofluorescent techniques, FN was demonstrated preferentially around migrating cells, and a protein synthesis inhibitor, cycloheximide, inhibited the migration by about 75%. FN produced by L-10 cells were found to be mostly EDA+ FN when analysed by RT-PCR. Moreover, anti-FN antibody, but not anti-vitronectin antibody, inhibited the TPA-induced cohort migration almost completely. Thus, it was likely that L-10 cells produced FN themselves and moved on the FN substrate in an RGD-dependent manner. However, stimulation of migration by type I collagen coating and inhibition by RGD treatment did not affect the tyrosine phosphorylation of the E-cadherin-catenin complex induced by TPA, indicating that cell-cell interactions were adjusted to suit cell migration, irrespective of the condition of cell-ECM adhesion, during TPA-induced cohort migration.

Expression of mRNA for heregulin and its receptor, ErbB-3 and ErbB-4, in human upper gastrointestinal mucosa

Expression of mRNA for heregulin (HRG), a member of the epidermal growth factor (EGF) family and its receptors, ErbB-3 and ErbB-4, were evaluated in human upper gastrointestinal (GI) mucosa. Multi-target reverse-transcriptase polymerase chain reaction (RT-PCR) analysis using capillary electrophoresis and laser-induced fluorescence allowed us to quantify the minute amounts of mRNA from one biopsy specimen with high sensitivity. HRG, ErbB-3 and ErbB-4 mRNA were detected in esophagus, stomach and duodenum and the highest expression was found in duodenum. In gastric cancer, mRNA for ErbB-4 was significantly overexpressed. Immunoreactivity of ErbB-4 in carcinoma cell membrane was also confirmed. These findings suggest that HRG and its receptors, ErbB-3 and ErbB-4 may be physiologically significant in the human upper GI mucosa, especially in duodenum, and that ErbB-4 may contribute to the growth of gastric cancer.

Up-regulation of vascular endothelial growth factor induced by hepatocyte growth factor/scatter factor stimulation in human glioma cells

Recent findings suggest that hepatocyte growth factor/scatter factor (HGF/SF) contributes to the malignant progression of human gliomas. We investigated the effect of HGF/SF on vascular endothelial growth factor (VEGF) expression of c-Met/HGF receptor-positive human glioma cell lines. Treatment of the glioma cells with various concentrations of HGF/SF resulted in an enhanced secretion of VEGF proteins accompanying increased transcription of VEGF mRNA in a dose-dependent fashion. Since malignant gliomas frequently co-express HGF/SF and its receptor, these results suggest that HGF/SF could act as an indirect angiogenic factor through autocrine induction of VEGF expression and secretion in malignant gliomas.

Expression of tissue factor in the rabbit aorta after balloon injury

Tissue factor (TF) is a primary initiator of the extrinsic pathway of blood coagulation. Recently TF has been shown to be overexpressed in atherosclerotic lesions and it is thought to contribute to the thrombogenicity of the plaques. We studied TF expression in the media and the neointima of rabbit aortas at various intervals after balloon injury. TF protein was immunohistochemically detected in smooth muscle cells (SMCs) of the inner layer of the media at 2 h after injury and was subsequently detected in SMCs in the neointima, whereas no TF expression was detected in the uninjured aortas except for the adventitia. Immunohistochemical and immunoelectron microscopic studies revealed that TF-positive SMCs were of an immature or synthetic phenotype and TF protein was detected in the rough endoplasmic reticulum in SMCs. TF mRNA in the intima and media increased at 2 h after injury and returned to near baseline levels at 12-24 h, whereas TF activity also increased at 2 h and continued at similar levels over the next 72 h. TF mRNA and activity increased markedly at 2-8 weeks after injury. These data suggest that TF is rapidly induced in the medial SMCs and hereafter is constitutively expressed in the neointima. TF expressed in the neointima may contribute to hypercoagulable properties of injured arteries.

Cell density-dependent regulation of fibronectin splicing at the EDA region in fibroblasts: cell density also modulates the responses of fibroblasts to TGF-beta and cancer cell-conditioned medium

Recently we reported that cancer cell-fibroblast interactions can modulate the expression of fibronectin (FN) isoforms in vitro, i.e. conditioned medium of human rectal adenocarcinoma cell line RCM-1 (RCM-1 CM) stimulated the expression of EDA-containing FN (EDA(+)FN) mRNA by fibroblasts and this stimulation was partly mediated by transforming growth factor-beta (TGF-beta) included in RCM-1 CM. In the present study, cell density was shown to regulate FN splicing at the EDA region in fibroblasts. Fibroblasts plated at a low cell density expressed a significantly higher percentage of EDA(+)FN mRNA than those plated at a high cell density. Moreover, fibroblast cell density modulated the effects of TGF-beta and RCM-1 CM on FN splicing at the EDA region differently. The time courses of their effects were similar to each other at a high cell density. At a low cell density, however, they were different. TGF-beta showed a relatively short-lived stimulation of EDA(+)FN mRNA, with the peak response 24 h after treatment, followed by a decline to the base line by 72 h. On the other hand, RCM-1 CM caused a prolonged stimulation, maintaining almost the maximum responses from 24 to 72 h. Thus, these results at a low cell density indicated the presence of a factor(s) other than TGF-beta in RCM-1 CM that stimulates the expression of EDA(+)FN mRNA directly or modulates the effect of TGF-beta. The use of several different cell densities might help in the search for new factors affecting FN splicing.

Evaluation of hepatocyte growth factor activator inhibitor expression in normal and malignant colonic mucosa

Gene expression of hepatocyte growth factor activator inhibitor (HAI), a recently identified Kunitz-type serine proteinase inhibitor, was analyzed in a series of human colorectal carcinoma cell lines and in human colorectal tissues. All of the 14 cell lines derived from adenocarcinoma of the colorectum expressed HAI in vitro, whereas a colon carcinoma cell line of neuroendocrine origin did not. In vivo, HAI was consistently expressed in the normal colorectal mucosa. Although the expression of HAI mRNA was conserved in adenocarcinoma tissues of the colorectum, the levels of expression were decreased in the adenocarcinoma tissues compared to the normal counterparts. There was a tendency towards an inverse correlation, albeit not well defined, between the amounts of HAI mRNA and the tumor progression. Immunohistochemical study indicated that HAI protein is present predominantly on the surface of epithelial cells of the colon and the immunoreactivity was decreased in the adenocarcinoma cells.

Effects of chronic inhibition of ACE and AT1 receptors on glomerular injury in dahl salt-sensitive rats

To elucidate the contribution of the renin-angiontensin system (RAS) to glomerular injury in salt-sensitive hypertension, we investigated the chronic effects of the angiotensin I-converting enzyme inhibitor cilazapril and the angiotensin II type 1-receptor antagonist (AT1a) TCV-116 in Dahl-Iwai rats. Dahl salt-sensitive (S) rats receiving 8% salt diet for 6 wk were simultaneously treated with cilazapril (n = 6), TCV-116 (n = 6), or saline (n = 14). The 8% salt diet markedly increased systolic blood pressure (SBP), urinary protein, and N-acetyl-beta-glucosaminidase (NAG) excretion compared with 0.3% salt-treated S (n = 6) or salt-resistant (n = 6) rats. Although neither cilazapril nor TCV-116 reduced the elevated SBP, TCV-116 significantly lowered urinary protein and NAG excretion. Histologically, 8% salt treatment in S rats induced progressive sclerotic and proliferative glomerular changes, which were ameliorated by both drugs. TCV-116 increased the glomerular diameter. Immunofluorescence demonstrated the increased level of type III collagen in the mesangium of 8% salt-treated S rats, which was completely reversed by TCV-116. Competitive RT-PCR of mRNA extracted from the glomeruli revealed that 8% salt treatment significantly increased the levels of proliferating cell nuclear antigen (PCNA) and platelet-derived growth factor B-chain and that TCV-116 significantly reduced the levels of PCNA and transforming growth factor-beta1 (TGF-beta1). Thus, although the chronic RAS-inhibition in salt-sensitive hypertension exerted a histologically renoprotective effect by both ways without lowering blood pressure, the RAS inhibition due to AT1a had more beneficial advantages of reducing proteinuria and attenuating the levels of glomerular TGF-beta1 and extracellular matrix.

In vitro generation of lymphohematopoietic cells from endothelial cells purified from murine embryos

We have investigated the lymphohematopoietic potentials of endothelial cells (EC) and hematopoietic cells (HPC) sorted from embryos. Expression of VE-cadherin, CD45, and Ter119 was used to distinguish EC (VE-cadherin+CD45-Ter119-) from HPC (VE-cadherin-CD45+). Thus defined, EC population takes up acetylated LDL and coexpresses CD31, Flk1, and CD34. In E9.5 embryos, EC from yolk sac (YS) and the embryo proper generate blood cells, including lymphocytes. Thus, lymphohematopoietic EC do exist in the embryo, and they are generated both in YS and the embryo proper. On the other hand, HPC with lymphopoietic potency appear first in the embryo proper. These findings implicate involvement of multiple environmental cues for acquiring lymphopoietic competency during differentiation of HPC.

FTY720, a novel immunosuppressant, induces sequestration of circulating mature lymphocytes by acceleration of lymphocyte homing in rats. II. FTY720 prolongs skin allograft survival by decreasing T cell infiltration into grafts but not cytokine production in vivo

FTY720, a novel immunosuppressant, prolonged the survival of WKAH skin allografts transplanted into MHC-incompatible F344 rats. In this allograft model, the median survival time of the control group was 7 days, whereas those of the groups given FTY720 orally at 0.1 mg/kg and cyclosporin A (CsA) at 10 mg/kg were 10.5 and 11 days, respectively. In contrast, FTY720 (0.1 mg/kg) combined with CsA (10 mg/kg) synergistically prolonged allograft survival with a median survival time exceeding 70 days. To elucidate the mechanisms of this remarkable synergistic effect, mRNA expressions of IL-2 and IFN-gamma and that of CD3 (delta-chain), which reflects T cell infiltration, in allografts were temporally analyzed using a semiquantitative PCR method. In WKAH skin allografts, mRNA levels of IL-2, IFN-gamma, and CD3 were increased as compared with isograft controls, peaking on days 4 to 5. CsA (10 mg/kg) significantly inhibited elevations of IL-2 and IFN-gamma mRNA, while slightly inhibiting that of CD3 mRNA in allografts. On the contrary, FTY720 (0.1 mg/kg) markedly inhibited the elevation of CD3 mRNA, while slightly inhibiting those of IL-2 and IFN-gamma mRNA. FTY720 (0.1 mg/kg) combined with CsA (10 mg/kg) almost completely suppressed the intragraft expressions of mRNA for IL-2, IFN-gamma, and CD3. Immunohistochemical staining and flow cytometric analysis also confirmed that FTY720 decreased T cell infiltration into allografts. From these results, the synergistic effect of FTY720 combined with CsA on prolongation of allograft survival is presumably based on the respective inhibitions of T cell infiltration and cytokine production in grafts.

FTY720, a novel immunosuppressant, induces sequestration of circulating mature lymphocytes by acceleration of lymphocyte homing in rats. I. FTY720 selectively decreases the number of circulating mature lymphocytes by acceleration of lymphocyte homing

FTY720, given i.v. or orally at 0.03 mg/kg or more, significantly prolonged skin allograft survival in a dose-dependent manner and showed more potent immunosuppressive activity than cyclosporin A (CsA) or tacrolimus (FK506) in MHC-incompatible rat strains of WKAH donors and F344 recipients. However, unlike CsA or FK506, FTY720 up to 1000 nM did not affect IL-2 production in allogeneic MLC. Within 3 to 24 h after a single oral administration of FTY720 at 0.1 to 1 mg/kg, the number of lymphocytes in the rats was markedly decreased in the peripheral blood and thoracic duct lymph and partially in spleen. By contrast, the number of lymphocytes in peripheral lymph nodes (PLN), mesenteric lymph nodes (MLN), and Peyer's patches (PP) was significantly increased at the same time. Intravenous transfusion of calcein-labeled rat lymphocytes into rats revealed that FTY720 significantly accelerated lymphocyte homing to PLN, MLN, and PP, dose dependently. Since FTY720-induced lymphocyte homing was completely blocked by simultaneous treatment of the calcein-labeled lymphocytes with mAbs against CD62L, CD49d, and CD11a before the transfusion, the acceleration of lymphocyte homing by FTY720 appears to be mediated by lymphocyte-homing receptors. These findings indicate that FTY720 sequesters circulating mature lymphocytes into PLN, MLN, and PP by acceleration of lymphocyte homing and thereby decreases the number of lymphocytes in peripheral blood, thoracic duct lymph, and spleen. Based on these observations, sequestration of circulating mature-lymphocytes is presumed to be a main mechanism of the immunosuppressive activity of FTY720.

Changes in osteoblast phenotype during differentiation of enzymatically isolated rat calvaria cells

Osteoblasts enzymatically isolated from newborn rat calvariae show various phenotypes including formation of mineralized bone nodules in culture. We investigated the temporal changes in osteoblast phenotype in these cells up to day 20 in culture. These cells formed unmineralized nodules by day 5. Mineralization was observed at the center of nodules by day 10, and nodules became larger on day 15. The nodules were surrounded by numerous alkaline phosphatase (ALP)-positive cells. ALP activity gradually increased by day 20. Parathyroid hormone (PTH) responsiveness increased with time in culture. Osteoblasts produced no osteocalcin by day 10, but its synthesis was detected from day 15. These cells expressed substantial levels of ALP and PTH/PTHrP receptor mRNAs as early as day 5 in culture, but very weak expression of osteocalcin mRNA on day 5. The levels of expression of these transcripts increased with time in culture. In situ hybridization demonstrated that PTH/PTHrP receptor and osteocalcin mRNAs were strongly expressed in nodules, but the former appeared much earlier than the latter. BMP-2 and BMP-4 mRNAs also appeared in the cells forming nodules. Immunohistochemical analysis demonstrated that cells expressing either BMP-2/4 or their receptors (BMPR-IA, BMPR-IB, and BMPR-II) preferentially appeared in nodules. These observations suggested that BMPs play an important role in the formation of mineralized bone nodules in an autocrine and/or paracrine fashion in these cells. The present study confirmed that osteoblasts enzymatically isolated from newborn rat calvariae are a useful tool for studying the differentiation process of osteoblasts.

Hematopoietic tissues, as a playground of receptor tyrosine kinases of the PDGF-receptor family

Three receptor tyrosine kinases of the PDGF receptor family (RTKP) that clustered within 1000 Kb of the mouse chromosome 5 constitute an interesting unit that are expressed in three distinct cell lineages essential for constructing hematopoietic tissues. Namely, the c-kit gene that is expressed in hematopoietic stem cells is flanked by pdgfr alpha and flk genes expressed respectively in stromal cells and vascular endothelial cells. In this article, we review our results on their expression in the embryonic hematopoietic tissues. We found that co-expression of Flkl and c-Kit was frequently detected either in vascular endothelial cells or hematopoietic cells in the early hematopoietic tissues. On the other hand, the three RTKPs are expressed in different cell lineages in the fetal liver. On the basis of this finding, we propose two modes of embryonic hematopoiesis; hematogenic angiopoiesis and hematopoiesis.

[A case of scleroderma renal crisis with massive pericardial effusion and positivity on antiphospholipid antibody test]

A 47-year-old woman was admitted to our hospital for evaluation of general fatigue and dyspnea. She had been diagnosed with progressive systemic sclerosis (PSS) when she was 39 years of age, on the basis of Raynaud's phenomenon, proximal sclerosis, and pigmentation of the skin. On admission, her blood pressure was 206/128 mmHg. Funduscopy revealed grade III (Keith & Wagener) hypertensive retinopathy. Laboratory data showed positivity for anti-nuclear antibody and anticardiolipin beta 2 glycoprotein I antibody, and the plasma level of renin activity (PRA) was abnormally high. Chest X-ray and UCG revealed massive pericardial effusion. On the second hospital day, she was operated on for pericardiodiaphragmatic fenestration. The volume of pericardial effusion amounted to more than 2000 ml. Post operative malignant hypertension persisted. Laboratory data showed thrombocytopenia, hemolytic anemia, and acute renal failure. We diagnosed scleroderma renal crisis (SRC) associated with antiphospholipid syndrome. Following the initiation of angiotensin converting enzyme inhibitor (ACE-I) combined with calcium antagonist and alpha-one blocker, her blood pressure and PRA decreased. She also had been treated with aspirin 81 mg daily. These therapies were effective in recovering the platelet count and stopped the progression of anemia and renal failure. Although either the finding of large pericardial effusion or SRC is associated with poor prognosis in PSS, this case has had a good clinical course. In this case, the findings suggested that anti-phospholipid antibody may have contributed to the pericarditis and SRC.

Renal AT1 receptor: autoradiographic localization and quantification in rat

To elucidate the precise localization of angiotensin II (Ang II) type 1 (AT1) receptors in the kidney, we utilized in vitro macro- and micro-autoradiography (ARG) of [3H]-Ang II bindings to the Wistar rat kidney in the presence of L-158,809, a specific non-peptide AT1 receptor antagonist. Besides, we estimated the density of renal AT1 receptors using the quantification of macro-ARG. The density of [3H]-Ang II binding to renal tissue was concentration-dependent in both renal cortex and medulla. Although the addition with 500 nM arginine vasopressin and 500 nM atrial natriuretic peptide had no effect on [3H]-Ang II, the total binding of [3H] Ang II completely displaced by the addition with 500 nM unlabeled Ang II or L-158,809. Macro-ARG revealed that the amount of both Ang II and AT1 receptors in the renal medulla greatly exceeded those in the renal cortex. In the medulla, the density of these receptors was not localized on the outer medulla but was confirmed mainly to the inner medulla, especially to the inner zone and longitudinal bands. Since the density and localization of AT1 receptors was consistent with that of total Ang II receptors, it appears that AT1 receptors comprise most of the Ang II receptors in the kidney. Micro-ARG revealed that Ang II receptors were mainly located in the glomerulus and proximal tubules of the renal cortex, as well as on the circumferences of vessels and the vasa recta of the renal medulla. The present study established a method for ARG of AT1 receptors in the kidney as well as a method for quantifying the macro-ARG.

An immunosuppressive regimen using FTY720 combined with cyclosporin in canine kidney transplantation

FTY720 induces apoptosis, specifically in lymphocytes, and prolongs allograft survival in rats and dogs. The purpose of this study was to define an effective range of FTY720 doses that could be combined with a suboptimal dose (10 mg/kg) of cyclosporin for canine kidney allograft recipients. The combination significantly prolonged allograft survival in all groups receiving FTY720 at a dose of 0.1, 0.3, 1.0, or 3.0 mg/kg. None of the recipients died due to notable side effects of the drug. In peripheral blood, the number of lymphocytes was extremely low, whereas the percentage of granulocytes increased during FTY720 administration. No significant difference in cyclosporin trough levels was observed between the cyclosporin-alone group and the combination groups. We conclude from the present study that FTY720 has a potent effect at an extremely low dose and a wide therapeutic window when combined with cyclosporin in canine kidney transplants.

Determination of amphetamine and methamphetamine in human hair by headspace solid-phase microextraction and gas chromatography with nitrogen-phosphorus detection

A simple and rapid method for the determination of amphetamine (AP) and methamphetamine (MA) in human hair was developed by headspace solid-phase microextraction (SPME) and gas chromatography with nitrogen-phosphorus detection (GC-NPD). The hair (1 mg) was dissolved in 0.2 ml of a 5 M sodium hydroxide solution in a tightly sealed vial by shaking at 75 degrees C for about 5 min. In order to adsorb AP and MA on the SPME fiber, 100 microm of polydimethylsiloxane fiber was exposed to the headspace of the vial, and the vial was heated at 55 degrees C for 20 min. Then the fiber was removed from the vial and inserted into the injection port of the GC-NPD system using a CBJ-17 capillary column. The compounds adsorbed on the fiber were analyzed by exposing the fiber at 220 degrees C for 30 s in the GC injection port. By using this method, AP and MA in human hair could be analyzed simply and rapidly without any interference from coexisting substances. The percentages of AP and MA extracted from human hair by the SPME method were 48 and 62%, respectively, and relative standard deviations were below 10% (n=5). The calibration curves for AP and MA were linear in the ranges of 0.4-15 and 4-160 ng/mg hair, respectively. The detection limits of AP and MA at a signal-to-noise ratio of three were 0.1 and 0.4 ng/mg hair, respectively. This method could be applied to the analysis of an abuser's hair sample.

Comparative analysis of expression of hepatocyte growth factor and its receptor, c-met, in gliomas, meningiomas and schwannomas in humans

Expression of hepatocyte growth factor (HGF) and c-met, a proto-oncogene that encodes a receptor for HGF, was examined in 45 cases of human primary intracranial tumors by means of RT-PCR. In gliomas, HGF and c-met mRNAs were preferentially expressed in high-grade tumors. Co-expression of both genes was observed in glioblastomas (6/15) and in one anaplastic astrocytoma (1/5) but not in low-grade astrocytomas (0/3). By contrast, the c-met gene was consistently expressed in meningiomas (12/14) and schwannomas (8/8). The presence of c-Met protein was confirmed in the tumor cells of glioblastoma, meningioma and schwannoma by immunohistochemical staining. Moreover, all of the schwannoma cases co-expressed the HGF gene. These observations suggest that HGF/c-met expression is somehow related to the disease progression in gliomas, whereas c-Met protein might have an important fundamental biological role in meningioma and schwannoma. Moreover, since all of the schwannoma cases concomitantly expressed the ligand (HGF) and the receptor (c-met) genes, HGF may act in an autocrine fashion in schwannoma.

[Ruptured aneurysm of the marginal branch of the superior cerebellar artery: case report]

The authors report a rare case of a ruptured aneurysm arising from the marginal branch of the left superior cerebellar artery. At the first retrosigmoid craniectomy carried out on the day of hospitalization, the clip was wrongly placed on the anterior inferior cerebellar artery (AICA). The unanticipated accident was due to incomplete dissection of a thick and severely adhered subarachnoid clot and the mistake was made because the course of the marginal artery was similar to that of the AICA. At the second operation undergone 1 week later, the aneurysm was easily and successfully clipped. After ventriculoperitoneal shunting, the patient returned to normal except for left hearing loss. The authors suppose that delayed surgery would be beneficial as a rule for ruptured aneurysms of the peripheral branch of the cerebellar arteries not only because dissection is easier but also because the risk of rebleeding and vasospasm are reported to be low in such aneurysms.

Effects of transglottal pressure change on fundamental frequency of phonation: preliminary evaluation of the effect of intraoral pressure change

The effect of transglottal pressure on the fundamental frequency of phonation was investigated in 14 subjects (12 adults and 2 children). A sudden change in intra-oral pressure was produced during sustained phonation. The effects of this pressure change were not monotonic, even within the modal register (around the upper end of the speaking range). The physical properties of the vocal folds related to the cricothyroid and thyroarytenoid muscles seemed to be important.

Apoptosis of medial smooth muscle cells in the development of saccular cerebral aneurysms in rats

BACKGROUND AND PURPOSE

Using an animal model, we examined the role of apoptosis in the disappearance of medial smooth muscle cells (SMCs) during the development and growth of cerebral aneurysms.

METHODS

Various degrees of cerebral aneurysms were induced in the right anterior cerebral artery-olfactory artery bifurcations in 65 Sprague-Dawley rats with ligation of the left common carotid artery and renal hypertension. We performed in situ end labeling of fragmented DNA with the lesions in 45 rats and electron microscopic study in the other 20 rats.

RESULTS

With in situ end labeling of fragmented DNA, 4+/-3 apoptotic medial SMCs were detected in 35 of the 45 bifurcations. Apoptotic SMCs appeared in the medial layer in the "preaneurysm" group, the site speculated to show an aneurysmal change in the near future (6+/-3), and in the media in the "early aneurysm" group, which showed characteristics such as a small depression (5+/-3). In the "progressive aneurysm" group, they appeared more frequently at the aneurysmal neck (3+/-2) than the dome (1+/-1). By electron microscopic study, shrunken medial SMCs exhibiting morphological apoptotic changes such as chromatin condensation and fragmentation of the cytoplasm and nucleus were observed in the preaneurysm and early aneurysm groups and at the neck portion in the progressive aneurysm group. In the aneurysmal dome, SMCs showed late characteristics of apoptosis such as more advanced nuclear and cytoplasmic condensation and formation of apoptotic bodies.

CONCLUSIONS

The present findings indicate that there is an association between apoptosis of medial SMCs and the formation of saccular cerebral aneurysms.

Immortalization of immunologically committed Epstein-Barr virus-transformed human B-lymphoblastoid cell lines accompanied by a strong telomerase activity

The immunological characteristics and immortalization processes of three EBV-transformed human B-lymphoblastoid cell lines, N0003, N0005 and N6803, with strong telomerase and infinitively proliferating activities are described. The three cell lines were apparently immortalized: they developed a strong telomerase activity at the population doubling levels (PDLs) between 11 and 135, and continued proliferation over 250 PDLs. All the cell lines expressed CD22, CD19 and CD20 antigens. They were uniformly stained with IgM (N0005), IgG (N6803) or IgA (N0003) at early PDLs between 17 and 20, and they secreted the corresponding class of Ig into the medium; the N6803 and N0003 cell lines continued to secrete each class of Ig at decreased levels while the N0005 cell line expressed or secreted virtually no Ig after immortalization. Karyotype analysis of the immortalized cell lines showed that they were derived from a single cell because they shared a set of abnormal chromosomes within each cell population, and two of the cell lines attained clonal characteristics before they developed a strong telomerase activity. These results indicate that the three immortalized cell lines with a strong telomerase activity correspond to the intermediate stages of B-cell differentiation naturally committed to a specific Ig class, and suggest that they were derived from a B-lymphoblastoid cell committed to a specific class of Ig with poor telomerase activity, rather than from a strongly telomerase-positive B-lymphoblastoid cell either committed or multipotential.

Expressions of PDGF receptor alpha, c-Kit and Flk1 genes clustering in mouse chromosome 5 define distinct subsets of nascent mesodermal cells

In gastrulating embryos, various types of cells are generated before differentiation into specific lineages. The mesoderm of the gastrulating mouse embryo represents a group of such intermediate cells. PDGF receptor alpha (PDGFRalpha), c-Kit and fetal liver kinase 1 (Flk1) are expressed in distinctive mesodermal derivatives of post-gastrulation embryos. Their expressions during gastrulation were examined by whole mount immunostaining with monoclonal antibodies against these three receptors. The antibodies stained different mesodermal subsets in gastrulating embryos. Flow cytometry of head fold stage embryos revealed that Flk1+ mesodermal cells could be further classified by the level of c-Kit expression. To examine the possibility that hematopoietic cell differentiation is initiated from the Flk1+ mesoderm, embryonic stem (ES) cells were cultured on the OP9 or PA6 stromal cell layer; the former but not the latter supported in vitro hematopoiesis from ES cells. Flk1+ cells were detected only on the OP9 cell layer from day 3 of differentiation before the appearance of hematopoietic cells. Thus, Flk1+ cells will be required for in vitro ES cell differentiation into hematopoietic cells. The results suggest that these three receptor tyrosine kinases will be useful for defining and sorting subsets of mesodermal cells from embryos or in vitro cultured ES cells.

Evidence for participation of gliostatin/platelet-derived endothelial cell growth factor in gastric ulcer healing

Gliostatin (GLS)/Platelet-derived endothelial cell growth factor (PD-ECGF) is a protein factor that has angiogenic and thymidine phosphorylase activity. It has been recently demonstrated to be related to disease activity in rheumatoid arthritis. However, its physiological role in the gastric mucosa is unknown. In the present study, concentrations of this protein in human gastric mucosa and plasma were evaluated. Further, the effect of purified human GLS/PD-ECGF on experimental ulcer healing was investigated in the rat. The human plasma concentration of GLS/PD-ECGF was significantly higher in patients with intractable gastric ulcer than in patients with significant resolution. The tissue content was significantly higher at the gastric ulcer edge than in either the fundic or pyloric region. GLS/PD-ECGF infusion delayed ulcer healing in a dose-dependent manner. These results suggest that gastric tissue and/or circulating GLS/PD-ECGF may participate in pathology and etiology of gastric ulcers and that this mechanism may relate to the pathogenesis of RA.