Flk1-positive cells derived from embryonic stem cells serve as vascular progenitors

Interaction between endothelial cells and mural cells (pericytes and vascular smooth muscle) is essential for vascular development and maintenance. Endothelial cells arise from Flk1-expressing (Flk1+) mesoderm cells, whereas mural cells are believed to derive from mesoderm, neural crest or epicardial cells and migrate to form the vessel wall. Difficulty in preparing pure populations of these lineages has hampered dissection of the mechanisms underlying vascular formation. Here we show that Flk1+ cells derived from embryonic stem cells can differentiate into both endothelial and mural cells and can reproduce the vascular organization process. Vascular endothelial growth factor promotes endothelial cell differentiation, whereas mural cells are induced by platelet-derived growth factor-BB. Vascular cells derived from Flk1+ cells can organize into vessel-like structures consisting of endothelial tubes supported by mural cells in three-dimensional culture. Injection of Flk1+ cells into chick embryos showed that they can incorporate as endothelial and mural cells and contribute to the developing vasculature in vivo. Our findings indicate that Flk1+ cells can act as 'vascular progenitor cells' to form mature vessels and thus offer potential for tissue engineering of the vascular system.

The prognostic significance of amplification and overexpression of c-met and c-erb B-2 in human gastric carcinomas

BACKGROUND

The c-met and the c-erb B-2 protooncogenes belong to a family of tyrosine kinase growth factor receptors. Abnormalities of these oncogenes and protein products have been reported in several cancers. The authors investigated the correlation between clinical factors and amplification or overexpression of the c-met and/or c-erb B-2 gene in Japanese patients with gastric carcinoma patients, with a focus on prognostic significance.

METHODS

Amplification and overexpression of c-met and c-erb B-2 were investigated retrospectively in 128 gastric carcinoma patients by using immunohistochemistry and Southern blot hybridization. Survival analysis was performed with the Kaplan-Meier test, and the log rank test was used for statistical analysis.

RESULTS

Overexpression of c-met and c-erb B-2 was observed in 46.1% and 16.4% of gastric carcinoma cases, respectively. Gene amplification of c-met and c-erb B-2 was detected in 10.2% and 11.7% of gastric carcinoma cases, respectively. Amplification and overexpression of c-met were correlated significantly with depth of tumor invasion and lymph node metastasis, whereas amplification and overexpression of c-erb B-2 were correlated significantly with histologic type. The survival rate of patients with amplification and/or overexpression of c-met or c-erb B-2 was significantly poorer than that of patients with no amplification or overexpression. Multivariate analysis revealed that c-met overexpression and lymph node metastasis were independent prognostic factors.

CONCLUSIONS

These data suggest that overexpression and/or gene amplification of c-met and c-erb B-2 may be prognostic factors in gastric carcinoma.

Vascular endothelial growth factor (VEGF) expression in human coronary atherosclerotic lesions: possible pathophysiological significance of VEGF in progression of atherosclerosis

BACKGROUND

Vascular endothelial growth factor (VEGF) is an important angiogenic factor reported to induce migration and proliferation of endothelial cells, enhance vascular permeability, and modulate thrombogenicity. VEGF expression in cultured cells (smooth muscle cells, macrophages, endothelial cells) is controlled by growth factors and cytokines. Hence, the question arises of whether VEGF could play a role in atherogenesis.

METHODS AND RESULTS

Frozen sections from 38 coronary artery segments were studied. The specimens were characterized as normal with diffuse intimal thickening, early atherosclerosis with hypercellularity, and advanced atherosclerosis (atheromatous plaques, fibrous plaques, and totally occlusive lesions). VEGF expression as well as the expression of 2 VEGF receptors, flt-1 and Flk-1, were studied with immunohistochemical techniques in these samples at the different stages of human coronary atherosclerosis progression. The expression of VEGF mRNA was also studied with reverse transcription-polymerase chain reaction. Normal arterial segments showed no substantial VEGF expression. Hypercellular and atheromatous lesions showed distinct VEGF positivity of activated endothelial cells, macrophages, and partially differentiated smooth muscle cells. VEGF positivity was also detected in endothelial cells of intraplaque microvessels within advanced lesions. In totally occlusive lesions with extensive neovascularization, intense immunostaining for VEGF was observed in accumulated macrophages and endothelial cells of the microvessels. Furthermore, VEGF mRNA expression was detected in atherosclerotic coronary segments but not in normal coronary segments. The immunostainings for flt-1 and Flk-1 were detected in aggregating macrophages in atherosclerotic lesions and also in endothelial cells of the microvessels in totally occlusive lesions.

CONCLUSIONS

These results demonstrate distinct expression of VEGF and its receptors (flt-1 and Flk-1) in atherosclerotic lesions in human coronary arteries. Considering the multipotent actions of VEGF documented experimentally in vivo and in vitro, our findings suggest that VEGF may have some role in the progression of human coronary atherosclerosis, as well as in recanalization processes in obstructive coronary diseases.

Possible participation of autocrine and paracrine vascular endothelial growth factors in hypoxia-induced proliferation of endothelial cells and pericytes

Hypoxia is the principal factor that causes angiogenesis. These experiments were conducted to explore how it induces the proliferation of vascular cells, a key step in angiogenesis. Human umbilical vein endothelial cells and bovine retinal pericytes were grown in controlled atmosphere culture chambers containing various concentrations of oxygen. The numbers of both endothelial cells and pericytes increased significantly under hypoxic conditions; the O2 concentrations that achieved maximal growth promotion were 10% for endothelial cells and 2.5% for pericytes. Quantitative reverse transcription-polymerase chain reaction analysis revealed that mRNAs coding for the secretory forms of vascular endothelial growth factor (VEGF), a mitogen specific to endothelial cells, were present in both endothelial cells and pericytes and that their levels increased significantly in the two cell types as the atmospheric O2 concentration decreased. The two genes for VEGF receptors, kinase insert domain-containing receptor (kdr) and fms-like tyrosine kinase 1 (flt1), were found to be constitutively expressed in endothelial cells, and their relative mRNA levels were ranked in that order. On the other hand, only flt1 mRNA was detected in pericytes under hypoxic conditions. Furthermore, most antisense oligodeoxyribonucleotides complementary to VEGF mRNAs efficiently inhibited DNA synthesis in endothelial cells cultured under hypoxic conditions. These results indicate that autocrine and paracrine VEGFs may take part in the hypoxia-induced proliferation of endothelial cells.

Inhibition of ischaemic hippocampal neuronal death in primates with cathepsin B inhibitor CA-074: a novel strategy for neuroprotection based on 'calpain-cathepsin hypothesis'

Although Cornu Ammonis (CA) 1 neurons of the hippocampus are known to be vulnerable to transient ischaemia, the mechanism of ischaemic neuronal death is still unknown, and there are very few strategies to prevent neuronal death at present. In a previous report we demonstrated micro-calpain activation at the disrupted lysosomal membrane of postischaemic CA1 neurons in the monkey undergoing a complete 20 min whole brain ischaemia. Using the same experimental paradigm, we observed that the enzyme activity of the lysosomal protease cathepsin B increased throughout the hippocampus on days 3-5 after the transient ischaemia. Furthermore, by immunocytochemistry cathepsin B showed presence of extralysosomal immunoreactivity with specific localization to the cytoplasm of CA1 neurons and the neuropil of the vulnerable CA1 sector. When a specific inhibitor of cathepsin B, the epoxysuccinyl peptide CA-074 (C18H29N3O6) was intravenously administered immediately after the ischaemic insult, approximately 67% of CA1 neurons were saved from delayed neuronal death on day 5 in eight monkeys undergoing 20 min brain ischaemia: the extent of inhibition was excellent in three of eight and good in five of eight monkeys. The surviving neurons rescued by blockade of lysosomal activity, showed mild central chromatolysis and were associated with the decreased immunoreactivity for cathepsin B. These observations indicate that calpain-induced cathepsin B release is crucial for the development of the ischaemic neuronal death, and that a specific inhibitor of cathepsin B is of potential therapeutic utility in ischaemic injuries to the human CNS.

cGMP-dependent protein kinase phosphorylates and inactivates RhoA

Small GTPase Rho and cGMP/cGMP-dependent protein kinase (cGK) pathways exert opposing effects in specific systems such as vascular contraction and growth. However, the direct interaction between these pathways has remained elusive. We demonstrate that cGK phosphorylates RhoA in vitro at Ser188, the same residue phosphorylated by cAMP-dependent protein kinase. In HeLa cells transfected with constitutively active cGK (C-cGK), stress fiber formation induced by lysophosphatidic acid or V14RhoA was blocked. By contrast, C-cGK failed to inhibit stress fiber formation in cells transfected with mutant RhoA with substitution of Ser188 to Ala. C-cGK did not affect actin reorganization induced by Rac1 or Rho-associated kinase, one of the effectors for RhoA. Furthermore, C-cGK expression inhibited the membrane translocation of RhoA. Collectively, our findings suggest that cGK phosphorylates RhoA at Ser188 and inactivates RhoA signaling. The physiological relevance of the direct interaction between RhoA and cGK awaits further investigation.

P-glycoprotein as the drug efflux pump in primary cultured bovine brain capillary endothelial cells

The expression of a functional P-glycoprotein (P-gp) which pumps drugs out of brain capillary endothelial cells (BCEC) into blood was studied by evaluating the steady-state uptake and efflux of vincristine (VCR) by primary cultured bovine BCEC. The steady-state uptake of VCR was increased in the presence of metabolic inhibitors, and an anti-P-gp monoclonal antibody, MRK16, as well as verapamil and steroid hormones which are known to reverse multidrug resistance in tumor cells. Furthermore, efflux of VCR from BCEC was inhibited by verapamil. By immunohistochemistry, P-gp was localized at the luminal side of the capillary endothelial cells in both gray matter of bovine brain and primary cultured BCEC. These data suggest that P-gp functions as a drug efflux pump at the luminal side of BCEC and regulates the transfer of certain lipophilic drugs from the blood into the brain.

Expression and tissue localization of membrane-type 1, 2, and 3 matrix metalloproteinases in human astrocytic tumors

Three different membrane-type matrix metalloproteinases (MT1-, MT2-, and MT3-MMPs) are known to activate in vitro the zymogen of MMP-2 (pro-MMP-2, progelatinase A), which is one of the key MMPs in invasion and metastasis of various cancers. In the present study, we have examined production and activation of pro-MMP-2, expression of MT1-, MT2-, and MT3-MMPs and their correlation with pro-MMP-2 activation, and localization of MMP-2, MT1-MMP, and MT2-MMP in human astrocytic tumors. The sandwich enzyme immunoassay demonstrates that the production levels of pro-MMP-2 in the anaplastic astrocytomas and glioblastomas are significantly higher than that in the low-grade astrocytomas (P<0.05 and P<0.01, respectively), metastatic brain tumors (P<0.05), or normal brains (P<0.01). Gelatin zymography indicates that the pro-MMP-2 activation ratio is significantly higher in the glioblastomas than in other astrocytic tumors (P<0.01), metastatic brain tumors (P<0.01), and normal brains (P<0.01). The quantitative reverse transcription polymerase chain reaction analyses demonstrate that MT1-MMP and MT2-MMP are expressed predominantly in glioblastoma tissues (17/17 and 12/17 cases, respectively), and their expression levels increase significantly as tumor grade increases. MT3-MMP is detectable in both astrocytic tumor and normal brain tissues, but the mean expression level is approximately 50-fold lower compared with that of MT1-MMP and MT2-MMP in the glioblastomas. The activation ratio of pro-MMP-2 correlates directly with the expression levels of MT1-MMP and MT2-MMP but not MT3-MMP. In situ hybridization indicates that neoplastic astrocytes express MT1-MMP and MT2-MMP in the glioblastoma tissues (5/5 cases and 5/5 cases, respectively). Immunohistochemically, MT1-MMP and MT2-MMP are localized to the neoplastic astrocytes in glioblastoma samples (17/17 cases and 12/17 cases, respectively), which are also positive for MMP-2. In situ zymography shows gelatinolytic activity in the glioblastoma tissues but not in the normal brain tissues. These results suggest that both MT1-MMP and MT2-MMP play a key role in the activation of pro-MMP-2 in the human malignant astrocytic tumors and that the gelatinolytic activity is involved in the astrocytic tumor invasion.

Significance of ventricular myocytes and nonmyocytes interaction during cardiocyte hypertrophy: evidence for endothelin-1 as a paracrine hypertrophic factor from cardiac nonmyocytes

BACKGROUND

In cardiac hypertrophy, both excessive enlargement of cardiac myocytes and progressive interstitial fibrosis are well known to occur simultaneously. In the present study, to investigate the interaction between ventricular myocytes (MCs) and cardiac nonmyocytes (NMCs), mostly fibroblasts, during cardiocytes hypertrophy, we examined the change in cell size and gene expression of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in cultured MCs as markers for hypertrophy in the neonatal rat ventricular cardiac cell culture system.

METHODS AND RESULTS

The size of cultured MCs significantly increased in the MC-NMC coculture. Concomitantly, secretions of ANP and BNP into culture media were significantly increased in the MC-NMC coculture compared with in the MC culture (with the possible contamination of NMC <1% of MC). Moreover, in the MC culture, enlargement of MC and an increase in ANP and BNP secretions were induced by treatment with conditioned media of the NMC culture. A considerable amount of endothelin (ET)-1 production was detected in the NMC-conditioned media. BQ-123, an ET-A receptor antagonist, and bosentan, a nonselective ET receptor antagonist, significantly blocked the hypertrophic response of MCs induced by treatment with NMC-conditioned media. Angiotensin II (Ang II) (10(-10) to 10(-6) mol/L) and transforming growth factor-beta1 (TGF-beta1) (10(-13) to 10(-9) mol/L), both of which are known to be cardiac hypertrophic factors, did not induce hypertrophy in MC culture, but both Ang II and TGF-beta1 increased the size of MCs and augmented ANP and BNP productions in the MC-NMC coculture. This hypertrophic activity of Ang II and TGF-beta1 was associated with the potentiation of ET-1 production in the MC-NMC coculture, and the effect of Ang II or TGF-beta1 on the secretions of ANP and BNP in the coculture was significantly suppressed by pretreatment with BQ-123.

CONCLUSIONS

These results demonstrate that NMCs regulate MC hypertrophy at least partially via ET-1 secretion and that the interaction between MCs and NMCs plays a critical role during the process of Ang II- or TGF-beta1-induced cardiocyte hypertrophy.

Shear stress augments expression of C-type natriuretic peptide and adrenomedullin

Shear stress is known to dilate blood vessels and exert antiproliferative effects on vascular walls: these effects have been ascribed to shear stress-induced upregulation of endothelium-derived vasoactive substances, mainly nitric oxide and prostacyclin. We have demonstrated the significance of C-type natriuretic peptide (CNP) as a novel endothelium-derived relaxing peptide (EDRP) that shares a cGMP pathway with nitric oxide. Adrenomedullin is a recently isolated EDRP that elevates intracellular cAMP as prostacyclin does. To elucidate the possible role of these EDRPs under shear stress, we examined the effect of physiological shear stress on CNP mRNA expression in endothelial cells derived from the human umbilical vein (HUVECs), bovine aorta (BAECs), and murine lymph nodes (MLECs) as well as adrenomedullin mRNA expression in HUVECs. CNP mRNA was stimulated prominently in HUVECs under shear stress of 15 dyne/cm2 in a time-dependent manner (4 hours, sixfold increase compared with that in the static condition; 24 hours, 30-fold increase). Similar results were obtained in BAECs (4 hours, twofold increase; 24 hours, threefold increase) and MLECs (4 hours, threefold increase; 24 hours, 10-fold increase). Augmentation of CNP mRNA expression that was dependent on shear stress intensity was also observed (5 dyne/cm2, 2.5-fold increase of static; 15 dyne/cm2, 4.5-fold increase). Increased CNP secretion was also confirmed by the specific radioimmunoassay for CNP. Adrenomedullin mRNA expression in HUVECs increased under shear stress of 15 dyne/cm2 in a time-dependent manner (4 hours, 1.2-fold increase of static: 24 hours, threefold increase) and shear stress intensity-dependent manner (15 dyne/cm2, threefold increase compared with that at 5 dyne/cm2). These results suggest that the coordinated augmentation of mRNA expression of these novel EDRPs may constitute shear stress-dependent vasodilator and antiproliferative effects.

Inhibition of rho-associated kinase results in suppression of neointimal formation of balloon-injured arteries

BACKGROUND

Rho-associated kinase (ROCK), an effector of small GTPase Rho, regulates vascular tone via a calcium sensitization mechanism and plays a key role in the pathogenesis of hypertension. However, its role in vascular growth remains unclear.

METHODS AND RESULTS

Y-27632, a specific ROCK inhibitor, and the overexpression of dominant-negative ROCK suppressed the mitogen-induced DNA synthesis of cultured vascular smooth muscle cells (VSMCs), which indicates the essential role of ROCK in the control of VSMC proliferation in vitro. Y-27632 also suppressed the chemotaxis of VSMCs. Male Wistar rats were systemically given Y-27632 (35 to 70 mg. kg(-1). day(-1)) through an intraperitoneal infusion. The neointimal formation of balloon-injured carotid arteries was significantly suppressed in Y-27632-treated rats (intima/media ratio, 0.22+/-0.02) compared with vehicle-treated rats (intima/media ratio, 0.92+/-0.21) or hydralazine-treated rats with a similar blood pressure decrease (intima/media ratio, 1.03+/-0.15). The phosphorylation of myosin phosphatase and myosin light chain was elevated in injured arteries in a Y-27632-sensitive manner, indicating the augmentation of ROCK activity in neointimal formation. The downregulation of the cyclin-dependent kinase inhibitor p27(kip1) in injured vessels was reversed by Y-27632 treatment, reflecting the antiproliferative effect of ROCK inhibition in vivo.

CONCLUSIONS

We conclude that ROCK plays a key role in the process of neointimal formation after balloon injury. Thus, the inhibition of ROCK may be a potential therapeutic strategy for treating vascular proliferative disorders and hypertension.

Intracranial and orbital cavernous angiomas. A review of 30 cases

The authors review 30 documented cases of intracranial and orbital cavernous angiomas treated at their institution between 1965 and 1984. The diagnosis was based on computerized tomography (CT) or surgery; three patients were treated in the pre-CT era (1965 to 1976) and 27 since the advent of CT. The number of cases diagnosed preoperatively markedly increased after the introduction of CT, and 22 cases were verified histopathologically at surgery. Six cases were in children (aged 2 months to 17 years) and 24 in adults (aged 19 to 73 years). There was no significant sex difference (male:female ratio was 14:16). Nineteen lesions were intraparenchymal, five were intraventricular, three were in the middle fossa, two were intraorbital, and one originated from the tentorium. Symptoms varied according to the site of the lesion; hemorrhage occurred in 11 cases. Calcifications were seen on CT scans in all cases, but on plain skull films in only two. Angiography revealed hypovascular masses in all cases excluding those with lesions in the middle fossa; in two cases, tumor stain could be detected only with prolonged-injection angiography. Radionuclide brain scanning showed a dense hot area in eight of 19 patients. Recent experience has shown that magnetic resonance imaging clarified anatomic relationships that were obscure on CT. The overall outcome was favorable except for one patient who died in the postoperative period. The clinical results in this series are summarized and some diagnostic and therapeutic problems are discussed.

Transient brain ischaemia provokes Ca2+, PIP2 and calpain responses prior to delayed neuronal death in monkeys

To clarify the mechanism of postischaemic delayed cornu Ammonis (CA)-1 neuronal death, we studied correlations among calpain activation and its subcellular localization, the immunoreactivity of phosphatidylinositol 4,5-bisphosphate (PIP2) and Ca2+ mobilization in the monkey hippocampus by two independent experimental approaches: in vivo transient brain ischaemia and in vitro hypoxia-hypoglycaemia of hippocampal acute slices. The CA-1 sector undergoing 20 min of ischaemia in vivo showed microscopically a small number of neuronal deaths on day 1 and almost global neuronal loss on day 5 after ischaemia. Immediately after ischaemia, CA-1 neurons ultrastructurally showed vacuolation and/or disruption of the lysosomes. Western blotting using antibodies against inactivated or activated mu-calpain demonstrated mu-calpain activation specifically in the CA-1 sector immediately after ischaemia. This finding was confirmed in the perikarya of CA-1 neurons by immunohistochemistry. CA-1 neurons on day 1 showed sustained activation of mu-calpain, and increased immunostaining for inactivated and activated forms of mu- and m-calpains and for PIP2. Activated mu-calpain and PIP2 were found to be localized at the vacuolated lysosomal membrane or endoplasmic reticulum and mitochondrial membrane respectively, by immunoelectron microscopy. Calcium imaging data using hippocampal acute slices showed that hypoxia-hypoglycaemia in vitro provoked intense Ca2+ mobilization with increased PIP2 immunostaining specifically in CA-1 neurons. These data suggest that transient brain ischaemia increases intracellular Ca2+ and PIP2 breakdown, which will activate calpain proteolytic activity. Therefore, we suggest that activated calpain at the lysosomal membrane, with the possible release of biodegrading enzyme, will cause postischaemic CA-1 neuronal death.

Treatment results of intracranial germinoma as a function of the irradiated volume

Between 1962 and 1986, 70 patients were treated with radiation for confirmed or suspected intracranial germinoma at our hospital. The diagnosis was based on histology in 30 cases, cerebrospinal fluid (CSF) cytology in 12 cases, and on clinical and radiological findings in the remaining 28 cases. The target of radiation was the primary tumor site in 34 cases (Group A), the entire neuraxis in 22 cases (Group B), the whole brain in 4 cases (Group C), and the ventricle plus spine in 6 cases (Group D). Four patients were not included in the above groups for various reasons. The average radiation dose was 50-55 Gy to the tumor, 30 Gy to the whole brain, and 24 Gy to the spinal axis. The 5- and 10-year survival rates of the 68 primary cases in which radiotherapy was completed were 86% and 79%, respectively. The survival and relapse-free survival rates for the above 4 groups did not differ significantly, although slightly better results were seen in Groups B and C. Five cases in Groups A and D developed intracranial recurrence, 4 adjacent to the primary site but 1 distant from it, whereas no intracranial recurrence was found in the whole-brain-treated groups (B and C). One patient in Group B developed spinal metastasis, which was possibly due to inadequate radiation fields, and another in Group B developed abdominal metastasis via the shunt tube. Craniospinal irradiation should be administered to the patients with demonstrated meningeal seeding or with a positive CSF cytology. For cytology-negative cases with no evident metastasis, irradiation of the tumor plus a wide margin is usually sufficient, but craniospinal irradiation should be considered when the disease extends along the ventricular walls or is present in both pineal and suprasellar regions.

Supratentorial low-grade astrocytoma. Correlation of computed tomography findings with effect of radiation therapy and prognostic variables

BACKGROUND

In supratentorial low-grade astrocytoma, radiation therapy effects and prognostic factors, especially with respect to computed tomography (CT) findings, are not yet well established. A retrospective analysis of 119 patients with this disease (histologically confirmed ordinary astrocytoma) therefore was conducted.

METHODS

Between 1965 and 1989, 101 patients received postoperative radiation therapy, whereas 18 patients received surgery alone. Radiation was directed to the tumor plus a 1- to 3-cm margin in almost all cases; the dose range was 41 to 66 Gy (mean, 57 Gy). CT scan was performed before treatment on 74 patients. Postoperative survival rates were compared by both univariate and multivariate analyses.

RESULTS

The 5- and 10-year survival rates for the irradiated group were 60% and 41%, respectively, which were significantly better than those for the surgery-alone group (37% and 11%, P = 0.048). Among various potential prognostic factors for the irradiated patients, only a lower age was associated with a better prognosis. Sex, tumor site (deep-seated or not), extent of surgery, radiation dose and field, and adjuvant chemotherapy did not influence the prognosis significantly. Among various CT findings, a clear tumor margin, a maximum tumor area less than 25 cm2, presence of a cyst, and lack of mass effect were associated with a better prognosis on univariate analysis (P = 0.02-0.12), but contrast enhancement was not related to prognosis. On multivariate analysis, however, mass effect was the only significant factor.

CONCLUSIONS

Radiation therapy appears definitely to be effective in improving the prognosis for low-grade astrocytoma. Younger age, and the absence of mass effect determined by CT, were associated significantly with a better prognosis.

Prognosis of intracranial germ cell tumours: effectiveness of chemotherapy with cisplatin and etoposide (CDDP and VP-16)

A co-operative study for patients with intracranial germ cell tumours was performed to analyze their prognosis and the effectiveness of Cisplatin/Etoposide (CDDP/VP-16) chemotherapy. A total of 46 patients; 30 primary and 16 recurrent cases were registered from 15 participating neurosurgical institutions in Japan. Based on histological criteria and tumour markers, they were classified into three groups; germinoma, germinoma with syncytiotrophoblastic giant cell (STGC), and non-germinomatous malignant tumour. Sixteen patients were treated with CDDP/VP-16 chemotherapy alone and the other 30 patients were treated by a combination of surgery and/or radiation in addition to chemotherapy. Eleven out of 13 patients (85%) with germinoma showed a complete (n = 10) or partial (n = 1) response to CDDP/VP-16 chemotherapy even if their tumours were recurrent and there was evidence of CSF dissemination. For the germinoma with STGC and non-germinomatous malignant tumour, a high response rate; 100% for the former and 78% for the latter, could also be achieved in both the primary and the recurrent cases except in those cases of immature teratoma. Their survival times were still different between them. Two-year survival was 50% in germinoma with STGC and 48% in non-germinoma, while it was 88% in germinoma cases.

In vivo and in vitro evidence for ATP-dependency of P-glycoprotein-mediated efflux of doxorubicin at the blood-brain barrier

We investigated the role of ATP in the active efflux of doxorubicin (DOX) mediated by P-glycoprotein (P-gp), the multidrug-resistance (MDR) gene product, at the blood-brain barrier. In transient brain ischemic rats prepared with 4-vessel occlusion of vertebral and common carotid arteries for 20 min, a procedure that depleted their brain ATP content to 3% that of normal rats, the estimated permeability coefficient of DOX was increased 17-fold (to 243 +/- 2.5 microL/min/g brain). When the ATP content recovered to a normal level by means of 30-min and 24-hr cerebral recirculation of blood, the permeability coefficient recovered to 14.0 +/- 5.0 and 18.4 +/- 2.3 microL/min/g brain (mean +/- SEM, N = 3-6), respectively, very close to the control permeability (14.3 +/- 1.5 microL/min/g brain). The uptake of DOX by primary cultured brain capillary endothelial cells expressing P-gp at the luminal membrane was increased significantly (up to 2-fold), which correlated well with the decrease of cellular ATP contents caused by treating the cells with metabolic inhibitors. Evidence for the ATP-dependent transport of DOX obtained from the present in vivo and in vitro studies strongly indicates that P-gp in the brain capillaries functions actively as an efflux pump in the physiological state, providing a major mechanism to restrict the transfer of DOX into the brain.

Overexpression of group II phospholipase A2 in human breast cancer tissues is closely associated with their malignant potency

Membrane-associated phospholipase A2 (M-PLA2) is an enzyme that hydrolyses the sn-2 fatty acyl ester bond of phosphoglycerides. We measured M-PLA2 concentration in tissue extracts from 325 human breast cancers using a specific radioimmunoassay recently developed. Correlation analyses between the tissue concentration of M-PLA2 and clinicopathological factors showed that the enzyme level was significantly higher in patients with distant metastasis than in those without. In addition, M-PLA2 concentration was significantly higher in scirrhous carcinoma than in other histological types. No significant association was found between M-PLA2 concentration and age, menstrual status, tumour size, histological grade, vessel involvement or oestrogen receptor (ER) and progesterone receptor (PR) status. The expression of M-PLA2 mRNA was examined in a fibroadenoma, a stage IV breast cancer and its metastatic site of skin. Northern blot analysis showed a clear hybridisation band corresponding to M-PLA2 mRNA in both primary breast cancer and its metastatic site, while the fibroadenoma expressed a faint band corresponding to M-PLA2 mRNA. Breast cancer patients with high M-PLA2 concentrations exhibited significantly shorter disease-free and overall survival than those with low M-PLA2 concentration at the cut-off point of 5 ng 100 mg-1 protein, which was determined in a separate study. In multivariate analysis, M-PLA2 was found to be an independent prognostic factor for disease recurrence and death in human breast cancer. The possible significance of M-PLA2 expression in human breast cancer tissue is discussed.

Detection of circulating tumor cells in patients with non-small cell lung cancer undergoing lobectomy by video-assisted thoracic surgery: a potential hazard for intraoperative hematogenous tumor cell dissemination

OBJECTIVE

We prospectively tested whether circulating tumor cells can be found in the preoperative, intraoperative, and postoperative peripheral blood of patients with resectable non-small cell lung cancer who undergo video-assisted lobectomy.

METHODS

We assayed for carcinoembryonic antigen messenger RNA (mRNA) by reverse transcriptase-polymerase chain reaction in the peripheral blood taken before, during, just after the completion of the lobectomy and then 2 to 3 weeks, and again 5 to 6 weeks, after the operation in 29 patients with pathologic stage I non-small cell lung cancer who underwent video-assisted lobectomy. We also analyzed the prognostic value of carcinoembryonic antigen mRNA expression pattern in an additional 57 patients with stage I non-small cell lung cancer, whose blood samples were previously assayed for carcinoembryonic antigen mRNA.

RESULTS

Of the 29 patients, the preoperative blood samples from 18 patients were negative for carcinoembryonic antigen mRNA. Of these 18 patients, 16 (89%) had positive test results during operation, although the remaining 2 patients (11%) consistently showed negative test results. The occurrence of this change from negative to positive tests results for carcinoembryonic antigen mRNA during video-assisted lobectomy was significantly higher than in patients who underwent open lobectomy in a previous study (18 of 35 patients; 51%; P <.001). In the 57 patients with stage I cancer whose blood samples were previously assayed for carcinoembryonic antigen mRNA, patients with persistently positive test results for carcinoembryonic antigen mRNA before and during operation had a significantly shorter survival when compared with those patients whose test results were persistently positive.

CONCLUSIONS

Video-assisted lobectomy, as compared with open lobectomy, for non-small cell lung cancer may increase the risk of seeding tumor cells into the circulation during operation.

Down regulation of peroxisome proliferator-activated receptorgamma expression by inflammatory cytokines and its reversal by thiazolidinediones

AIMS/HYPOTHESIS

Previous studies show that inflammatory cytokines play a part in the development of insulin resistance. Thiazolidinediones were developed as insulin-sensitizing drugs and are ligands for the peroxisome proliferator-activated receptory (PPARgamma). We hypothesized that the anti-diabetic mechanism of thiazolidinediones depends on the quantity of PPARgamma in the insulin resistant state in which inflammatory cytokines play a part.

METHODS

We isolated rat PPARgamma1 and gamma2 cDNAs and examined effects of various cytokines and thiazolidinediones on PPARgamma mRNA expression in rat mature adipocytes.

RESULTS

Various inflammatory cytokines, such as tumour necrosis factor-alpha (TNF-alpha), interleukin-1alpha (IL-1alpha), IL-1beta, IL-6 and leukaemia inhibitory factor decreased PPARgamma mRNA expression. In addition, hydrogen peroxide, lysophosphatidylcholine or phorbol 12-myristate 13-acetate also decreased the expression of PPARgamma. The suppression of PPARgamma mRNA expression caused by 10 nmol/l of TNF-alpha was reversed 60% and 55% by treatment with 10(-4) mol/l of troglitazone and 10(-4) mol/l of pioglitazone, respectively. The suppression of glucose transporter 4 mRNA expression caused by TNF-alpha was also reversed by thiazolidinediones. Associated with the change of PPARgamma mRNA expression, troglitazone improved glucose uptake suppressed by TNF-alpha.

CONCLUSION/INTERPRETATION

Our study suggests that inflammatory cytokines could be factors that regulate PPARgamma expression for possible modulation of insulin resistance. In addition, we speculate that the regulation of PPARgamma mRNA expression may contribute to the anti-diabetic mechanism of thiazolidinediones.

Immunohistochemical expression of the c-kit proto-oncogene product in human malignant and non-malignant breast tissues

The immunohistochemical expression of c-kit proto-oncogene product in 57 breast cancer tissues was studied using anti-c-kit proto-oncogene product antibody in comparison with 20 normal breast tissues and 58 benign breast tumours. In normal breast tissues, the c-kit proto-oncogene product was strongly expressed on cell membrane and/or cytoplasm of alveolar and ductal cells. The immunoreactive score (IRS) of c-kit proto-oncogene product in normal mammary epithelia was 6.22 +/- 2.11 (mean +/- s.d.). In benign breast diseases, the c-kit proto-oncogene product was detected heterogeneously with a reduced IRS (3.33 +/- 2.44). In breast cancer tissues, the expression of the immunoreactive c-kit proto-oncogene product was often deleted and the average IRS was significantly reduced compared to those of normal breast tissues or benign breast diseases tissues. Among benign diseases, the average IRS of intraductal papilloma was significantly reduced (1.34 +/- 1.70) and the staining intensity and pattern were found to be similar to those seen in breast cancer. The results in this study suggested that the c-kit proto-oncogene product is correlated with the growth control or the differentiation of normal breast epithelium. Also, the loss of the expression of this protein may indicate the change of the signal transduction in relation to malignant transformation in human mammary epithelium.

Thiazolidinediones, peroxisome proliferator-activated receptor gamma agonists, regulate endothelial cell growth and secretion of vasoactive peptides

Insulin resistance has been highlighted as a common causal factor for glucose intolerance, hypertension and dyslipidemia, all of which are cardiovascular risk factors. A new class of antidiabetic agents, thiazolidinediones (TZDs), has been developed and demonstrated to improve insulin sensitivity. TZDs are high affinity ligands for peroxisome proliferator-activated receptor gamma (PPARgamma), the crucial transcription factor for adipocytes. Recent studies showed that PPARgamma is also expressed in monocytes/macrophages and is suggested to be involved in atherosclerosis. We could detect PPARgamma gene transcript in several cultured endothelial cells (human aortic endothelial cells (HAoECs), human coronary artery endothelial cells (HCAECs), human umbilical vein endothelial cells (HUVECs) and bovine carotid artery endothelial cells (BAECs)) as well as human coronary arteries we examined. Since endothelial dysfunction is critical for atherosclerosis, we investigated the effects of TZDs, troglitazone (TRO) and pioglitazone (PIO), on endothelial cell growth and secretion of C-type natriuretic peptide (CNP), which we demonstrated as a novel endothelium-derived relaxing peptide, and endothelin (ET), a potent vasoconstrictor, using HAoECs, HCAECs, HUVECs and BAECs. When all these cultured endothelial cells were daily treated with TRO and PIO for 5 days, both TRO and PIO (10(-8)M) significantly stimulated (3)H-thymidine incorporation of all these endothelial cells. In contrast, higher dose of TRO and PIO (10(-5)M) significantly suppressed DNA synthesis. TRO and PIO also exerted the compatible effect on the increase of cell numbers. TRO and PIO significantly enhanced CNP secretion from BAECs. In contrast, ET secretion from BAECs was suppressed by both TRO and PIO in a dose-dependent manner. The results of the present study suggest that TZDs modulate endothelial functions, including regulation of endothelial cell growth and secretion of endothelium-derived vasoactive substances, which affect vascular tone and remodeling in the process of atherosclerosis.

Clinicopathologic evaluation of immunohistochemical E-cadherin expression in human gastric carcinomas

BACKGROUND

E-cadherin plays a crucial role in cell-cell adhesion in epithelial tissues. Recent studies have shown a correlation between decreased E-cadherin expression and cancer cell detachment.

METHODS

The expression of E-cadherin was immunohistochemically analyzed using antihuman E-cadherin antibody in 121 cases of human gastric carcinoma.

RESULTS

In noncancerous areas, the epithelial cells, including those with intestinal metaplasia, were stained positively in the plasma membrane. In contrast, E-cadherin expression of the cancer cells varied from case to case in primary and secondary sites. Tumors with a decrease in E-cadherin occurred significantly more frequently in undifferentiated adenocarcinoma (P < 0.05) and scirrhous type (P < 0.01). The rate of E-cadherin-negative tumors was higher in patients with peritoneal metastasis (P < 0.01) or in those with distant lymph node metastasis (P < 0.01), though the tumors with liver metastasis had relatively positive E-cadherin expression. Patterns of initial recurrence had similar results. Reduction or loss of E-cadherin expression correlated with shorter survival in patients after curative operation regardless of stage of disease.

CONCLUSIONS

The decreased E-cadherin expression correlates with dedifferentiation, infiltrative tumor growth, distant metastasis, and poor survival for patients with gastric carcinoma. Thus, immunohistochemical study of E-cadherin may have clinicopathologic value for patients with gastric carcinoma.

Single neuron responses in the monkey anterior cingulate cortex during visual discrimination

Single neuron activity was recorded from the monkey anterior cingulate cortex during operant behavior based on discrimination of rewarding, aversive, and neutral objects. Of 550 neurons recorded, 116 responded during the task; 36, during visual discrimination; 40, during bar pressing for operant responding. Of these, 26 vision-related neurons responded differentially to rewarding, aversive and neutral objects, and 11 bar press-related neurons differentiated bar pressing to avoid shock from bar pressing to obtain reward. Responses of these neurons depended on associative meaning (aversive or rewarding) of the objects since these neuronal responses were modulated by the reversal learning. The results provide neuronal bases for involvement of the anterior cingulate cortex in emotional and motivational processes.

The use of dynamic mechanical analysis to assess the viscoelastic properties of human cortical bone

The purpose of this study was to examine the use of a dynamic mechanical analyzer (DMA) system to study the viscoelastic nature of bone. Cortical bone specimens from human femora were tested isothermally for 150 min at 37 degrees C and the loss factor (tan delta) and storage modulus (E') were measured. To explore the effects of test conditions on tan delta and E', different levels of applied stress, two specimen sizes, and two hydration conditions (wet and vacuum-dried) were evaluated. Finally, nonisothermal tests were performed, wherein specimens were heated up to 70 degrees C at different heating rates: 1 degrees C/min, 3 degrees C/min, and 5 degrees C/min. The results indicated that a threshold level of minimum applied stress was required to obtain repeatable and relatively constant values of tan delta. Specimen size did not significantly affect tan delta although it influenced E'. Moisture content had a significant effect on tan delta; vacuum-dried specimens exhibited a lower tan delta compared to wet specimens. Lastly, heating rates influenced tan delta values with lower rates producing more consistent results. The study demonstrated that DMA can be used as an effective tool to test bone.