Relationship between cytotoxicity,drug accumulation,DNA damage and repair of human ovarian cancer cells treated with doxorubicin: modulation by the tiapamil analog RO11-2933

Summary The effect ofN-(3,4-dimethoxyphenyl)N-methyl-2-(naphthyl)-m-dithiane-2-propylamine hydrochloride (RO11-2933), an analog of the calcium channel blocker tiapamil, on doxorubicin (DOX)-induced cytotoxicity and DNA damage in human ovarian cancer cells sensitive and resistant to DOX was investigated. A2780-DX2, A2780-DX3, and A2780-DX6 cell sublines were characterized by 7-, 26-, and 48-fold resistance after 2 h DOX exposure and 30-, 50-, and 500-fold resistance after 72 h DOX exposure, respectively. Increased drug efflux resulting in a lower intracellular drug accumulation, decreased DOX-induced DNA single-strand breaks (DNA SSBs), and rapid DNA repair correlated with the degree of resistance. In addition, DNA SSBs were rapidly repaired within 8 h in A2780-DX3 cells, whereas no significant repair of DNA SSBs was observed in sensitive cells. In comparison with verapamil, RO11-2933 was found to reverse DOX resistance at lower and nontoxic concentrations (2 M as compared with 10 M verapamil). This reversion was complete in cells with a low degree of resistance (A2780-DX1 and A2780-DX2) but partial in highly resistant cells (A2780-DX3 and A2780-DX6), and continuous exposure to RO11-2933 was essential for optimal reversal of drug resistance. Interestingly, RO11-2933 was found to inhibit the repair of DNA SSBs induced by DOX but not those induced by X-ray. These results suggest that the potentiation of DNA SSBs and the specific inhibition of DNA repair by RO11-2933 in multidrug-resistant cells could be of particular value in overcoming MDR in the clinic.Abbreviations RO11-2933 N-(3,4-dimethoxyphenethyl)-N-methyl-2-(2-naphthyl)-m-dithiane-2-propylamine hydrochloride - DOX doxorubicin-HCl - SSBs single-strand breaks - MDR multidrug resistance This work was supported in part by CA 18420 and CA 21071     

Region-specific growth properties and trophic requirements of brain- and spinal cord-derived rat embryonic neural precursor cells

To determine whether neural precursor cells have region-specific growth properties, we compared the proliferation, mitogenicity, and differentiation of these cells isolated from the embryonic day 16 rat forebrain and spinal cord. Neural precursor cells isolated from both regions were cultured in growth medium supplemented with epidermal growth factor, basic fibroblast growth factor, or epidermal growth factor+basic fibroblast growth factor. Under all three conditions, both neural precursor cell populations proliferated for multiple passages. While spinal cord-derived neural precursor cells proliferated moderately faster in epidermal growth factor-enriched growth medium, brain-derived cells proliferated much faster in basic fibroblast growth factor-enriched growth medium. When exposed to both epidermal growth factor and basic fibroblast growth factor, the two neural precursor cell populations expanded and proliferated more rapidly than when exposed to a single factor, with brain-derived neural precursor cells expanding significantly faster than spinal cord-derived ones (P<0.0001). Differentiation studies showed that both neural precursor cell populations were multi-potent giving rise to neurons, astrocytes, and oligodendrocytes. However, neuronal differentiation from brain-derived neural precursor cells was greater than spinal cord-derived ones (11.95+/-5.00% vs 1.92+/-1.13%; passage 2). Further, the two neural precursor cell populations differentiated into a similar percentage of oligodendrocytes (brain: 8.66+/-5.85%; spinal cord: 7.69+/-3.91%; passage 2). Immunofluorescence and Western blot studies showed that neural precursor cells derived from both regions expressed receptors for basic fibroblast growth factor and epidermal growth factor. However, brain-derived neural precursor cells expressed higher levels of the two receptors than spinal cord-derived ones in growth medium containing epidermal growth factor+basic fibroblast growth factor. Thus, our results showed that neural precursor cells isolated from the two regions of the CNS have distinct properties and growth requirements. Identifying phenotypic differences between these neural precursor cell populations and their growth requirements should provide new insights into the development of cell therapies for region-specific neurological degenerative diseases.     

Effects of x-ray and CT image enhancements on the robustness and accuracy of a rigid 3D/2D image registration

A rigid body three-dimensional/two-dimensional (3D/2D) registration method has been implemented using mutual information, gradient ascent, and 3D texturemap-based digitally reconstructed radiographs. Nine combinations of commonly used x-ray and computed tomography (CT) image enhancement methods, including window leveling, histogram equalization, and adaptive histogram equalization, were examined to assess their effects on accuracy and robustness of the registration method. From a set of experiments using an anthropomorphic chest phantom, we were able to draw several conclusions. First, the CT and x-ray preprocessing combination with the widest attraction range was the one that linearly stretched the histograms onto the entire display range on both CT and x-ray images. The average attraction ranges of this combination were 71.3 mm and 61.3 deg in the translation and rotation dimensions, respectively, and the average errors were 0.12 deg and 0.47 mm. Second, the combination of the CT image with tissue and bone information and the x-ray images with adaptive histogram equalization also showed subvoxel accuracy, especially the best in the translation dimensions. However, its attraction ranges were the smallest among the examined combinations (on average 36 mm and 19 deg). Last the bone-only information on the CT image did not show convergency property to the correct registration.     

Genetic imbalances in pleomorphic xanthoastrocytoma detected by comparative genomic hybridization and literature review.

Pleomorphic xanthoastrocytoma (PXA) is a rare, low-grade astrocytic tumor found in the central nervous system. Histologically, the tumor is characterized by markedly pleomorphic and lipidized cells. Although most of the patients have a favorable prognosis, a small number of cases undergoing recurrence or progression to anaplastic astrocytoma were reported. Very few genetic studies have been performed on PXA because of its rarity and the pathogenesis of this neoplasm is largely unknown. In order to provide an overview of genetic alterations in PXA, we performed comparative genomic hybridization to identify chromosomal imbalances (DNA gains and losses) in three cases of PXA. Genetic imbalance was detected on at least one chromosome for each case. One case, which revealed multiple genetic alterations, showed a poor prognosis. DNA gain on chromosome 7 and loss on 8p were demonstrated in two of three cases, suggesting that the candidate gene(s) located on these regions may play a role in the development of PXA. Further studies are needed to identify the residing candidate genes that are involved in the tumorigenesis of PXA. In addition, the histopathological features and previous genetic studies on PXA are reviewed.     

多脏器恶性肿瘤术后肝黏膜相关淋巴组织淋巴瘤

目的 探讨肝黏膜相关淋巴组织淋巴瘤的临床病理特征。方法 对1例罕见多脏器恶性肿瘤术后肝黏膜相关淋巴瘤病例结合文献进行临床、病理和免疫组化分析。结果 患者于8年和3年前先后发生胃恶性间质瘤、阴囊阴茎皮肤湿疹样癌，有长期化疗史。肿瘤组织学以单核样B细胞为主，并有淋巴滤泡和淋巴上皮病变形成。免疫表型示瘤细胞CD45、CD79α、CD20阳性，CD5、CD10、ALK、TdT阴性，bcl—2、Ki—67少数肿瘤细胞阳性。结论 肝黏膜相关淋巴瘤可以发生于多脏器恶性肿瘤术后，其发病可能与长期使用免疫抑制剂有关，诊断本病时需与肝继发性淋巴瘤及肝的炎性假瘤鉴别。     

汉族人群载脂蛋白CII基因二核苷酸串联重复序列(TG)n(AG)m及(AG)m多态性

采用套式聚合酶链反应结合变性聚丙烯酰胺凝胶电泳和银染技术，并构建载脂蛋白CII（ApoCII)基因二核苷酸串联重复序列（TG）n(AG)m及（AG）m序列等位基因梯阶标准；检测正常汉族人群基因型和等位基因频率分布，检出36种（TG）n(AG)m序列基因型、12种等位基因。等位基因为17、18、26－35，其频率分别为0．061、0．011、0．002、0．002、0．054、0．255、0．372、0．084、0．026、0．039、0．052、0．041。检出7种（AG）m序列基因型、4种等位基因。等位基因为6、7、8、9，其频率分别为0．002、0．152、0．812、0．034。与欧洲白种人比较，ApoCII基因二核苷酸串联重复序列（TG）n(AG)m及（AG）m序列等位基因频率分布均具有明显的种族差异性（P＜0．01，P＜0．01）。     

To die or not to die for neurons in ischemia,traumatic brain injury and epilepsy: a review on the stress-activated signaling pathways and apoptotic pathways

After a severe episode of ischemia, traumatic brain injury (TBI) or epilepsy, it is typical to find necrotic cell death within the injury core. In addition, a substantial number of neurons in regions surrounding the injury core have been observed to die via the programmed cell death (PCD) pathways due to secondary effects derived from the various types of insults. Apart from the cell loss in the injury core, cell death in regions surrounding the injury core may also contribute to significant losses in neurological functions. In fact, it is the injured neurons in these regions around the injury core that treatments are targeting to preserve. In this review, we present our cumulated understanding of stress-activated signaling pathways and apoptotic pathways in the research areas of ischemic injury, TBI and epilepsy and that gathered from concerted research efforts in oncology and other diseases. However, it is obvious that our understanding of these pathways in the context of acute brain injury is at its infancy stage and merits further investigation. Hopefully, this added research effort will provide a more detailed knowledge from which better therapeutic strategies can be developed to treat these acute brain injuries.     

High density of immobilized galactose ligand enhances hepatocyte attachment and function

Galactosylated surface is an attractive substrate for hepatocyte culture because of the specific interaction between the galactose ligand and the asialoglycoprotein receptor on hepatocytes. In this study, we described a scheme to achieve high density of immobilized galactose ligands on polyethylene terephthalate (PET) surface by first surface-grafting polyacrylic acid on plasma-pretreated PET film under UV irradiation, followed by conjugation of a galactose derivative (1-O-(6'-aminohexyl)-D-galactopyranoside) to the grafted polyacrylic acid chains. A high galactose density of 513 nmol/cm(2) on the PET surface was used in this study to investigate the behavior of cultured hepatocyte. This engineered substrate showed high affinity to fluorescein isothiocyanate-lectin binding. Primary rat hepatocytes, when seeded at a density of 2 x 10(5) cells/cm(2), attached to the galactosylated PET substrate at a similar efficiency compared with collagen-coated substrate. The hepatocytes spontaneously formed aggregates 1 day after cell seeding and showed better maintenance of albumin secretion and urea synthesis functions than those cultured on collagen-coated surface.     

小儿肝的年龄解剖学研究

分六个年龄组观察了180个(男98,女82)小儿肝的形态、度量、位置及体表投影.小儿肝相对较大,右叶大于左叶,下界位置较低并逐渐上移.在右锁骨中线的肋弓下一般均可触到.小儿肝重随其年龄(身高)的增长而增长,其增长速度相对较慢,尤以Ⅶ组小儿更明显.     

Adhesion contact dynamics of HepG2 cells on galactose-immobilized substrates

The specific recognition between asialoglycoprotein receptor and galactose ligand at cell-substrate interfaces has been shown to mediate hepatocyte adhesion and maintain liver specific functions of hepatocytes. Conventionally, the success of hepatocyte attachment on engineered tissue scaffold is inferred from the degree of two-dimensional cell spreading that is measured by transmitted light microscopy. However, the actual contact mechanics and adhesion strength of hepatocytes during two-dimensional cell spreading has not been elucidated due to lack of biophysical probe. In this study, a novel biophysical technique known as confocal reflectance interference contrast microscopy (C-RICM) in conjunction with phase contrast microscopy is utilized to probe the adhesion dynamics, contact mechanics and two-dimensional spreading kinetics of HepG2 cells on galactose immobilized and collagen gel coated substrates. C-RICM demonstrates that HepG2 cells form strong adhesion contacts with both galactose-immobilized surfaces and collagen gel coated substrates. Moreover, HepG2 cells maintain their compact shapes in the presence of asialoglycoprotein receptor-mediated recognition while they become exceedingly spread under integrin-mediated adhesion on collagen gel coated substrate. The initial rate of adhesion contact formation and the steady-state adhesion energy of HepG2 cell population are highest on substrate conjugated with galactose ligand via a longer spacer. The adhesion dynamics and final adhesion energy of HepG2 cells depends both on the type of ligand-receptor interaction and the length of spacer between the ligand and substrate. Most importantly, new biophysical insights into the initial hepatocyte attachment that are critical for hepatocyte culture are provided through the decomposition of two-dimensional spreading and adhesion contact formation on bio-functional substrates.