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Presents information on a study that examined the lateral spreading of implantation-induced damage. Position dependence of the cathodoluminescence intensity of gallium arsenide (GaAs)/aluminum arsenide heterostructures patterned by a focused gallium[sub+] ion beam. Measurement techniques to study the focused ion beams-induced damage; Dose dependence and the effect of rapid thermal annealing; Spatial dependence of the mobility of the two-dimensional electron gas at an AlGaAs/GaAs.

Copyright of Der Pathologe is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We have earlier described the oncolytic adenovirus vector dl520 that was rendered cancer-specific by deletion of the transactivation domain CR3 of the adenoviral E1A13S protein; this deletion causes antitumor activity in drug-resistant cells displaying nuclear YB-1 expression. We hypothesized that the anticancer activity of dl520 could be further improved by introducing the RGD motif in the fiber knob and by deletion of the adenoviral E1B19K protein (Ad-Delo3-RGD). In this study, the in vitro and in vivo antitumor activity of Ad-Delo3-RGD was investigated focussing on two pancreatic cancer cell lines MiaPaCa-2 and BxPC3 alone and in combination with cytotoxic drugs. Furthermore, luciferin-based bioluminescence imaging was established to study the therapeutic response in vivo. In addition, to confirm the specificity of Ad-Delo3-RGD for YB-1 a tetracycline-inducible anti-YB-1 shRNA-expressing cell variant EPG85-257RDB/tetR/YB-1 was used. This TetON regulatable expression system allows us to measure adenoviral replication by real-time PCR in the absence of YB-1 expression. The results confirmed the YB-1 dependency of Ad-Delo3-RGD and showed that Ad-Delo3-RGD has potent activity against human pancreatic cancer cells in vitro and in vivo, which was augmented by the addition of paclitaxel. However, although high replication capacity was measured in vitro and in vivo, complete tumor regression was not achieved, indicating the need for further improvements to treat pancreatic cancer effectively. [ABSTRACT FROM AUTHOR]

Copyright of Der Pathologe is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Although various mechanisms involved in anticancer multidrug resistance (MDR) can be identified, it remains a major problem in oncology. Beyond that, the introduction of new “targeted” drugs have not solved the problem. On the contrary, it has been demonstrated that the “classical” MDR-associated mechanisms are similar or identical to those causing resistance to these novel agents. These mechanisms include the enhanced activity of drug pumps, i.e. ABC or alternative transporters; modulation of cellular death pathways; alteration and repair of target molecules; and various less common mechanisms. Together they build a complex network of cellular pathways and molecular mechanisms mediating an individual MDR phenotype. Although the application of new high throughput “-omics” technologies have identified multiple new gene-/protein expression signatures or factors associated with drug resistance, so far none of these findings has been useful for creating improved diagnostic assays, for prediction of individual therapy response, or for development of updated chemosensitizers. [ABSTRACT FROM AUTHOR]

Determination of oestrogen receptor alpha (ER) represents at present the most important predictive factor in breast cancers. Data of ours and of other authors suggest that promising predictive/prognostic factors may also include pS2, metallothionein (MT) and CD24. Present study aimed at determining prognostic and predictive value of immunohistochemical determination of ER, pS2, MT, and CD24 expression in sections originating from 104 patients with breast cancer. An univariate and multivariate analysis was performed. Both univariate and multivariate analyses demonstrated that cytoplasmic-membranous expression of CD24 (CD24c-m) represents a strong unfavourable prognostic factor in the entire group and in most of the subgroups of patients. In several subgroups of the patients also a prognostic value was demonstrated of elevated expression of pS2 and of membranous expression of CD24. Our studies demonstrated that all patients with good prognostic factors (higher ER and pS2 expressions, lower MT expression, CD24c-m negativity) survived total period of observation (103 months). The study documented that cytoplasmic-membranous expression of CD24 represented an extremely strong unfavourable prognostic factor in breast cancer. Examination of the entire panel of the studied proteins permitted to select a group of patients of an exceptionally good prognosis. [ABSTRACT FROM AUTHOR]

A monoclonal mouse antibody, Be-F4, was generated by means of immunization with a synthetic oligopeptide. In Western blots, this antibody recognizes an antigen with an apparent molecular mass of 62 kDa, termed p62. Immunohistochemical analysis of p62 in hepatocellular carcinoma (HCC) specimens (n=33) and in corresponding non-cancerous liver tissue was performed using monoclonal antibody Be-F4. All non-neoplastic hepatic cells showed, without exception, a moderate or strong staining intensity of the 62-kDa antigen, recognized by Be-F4. In contrast to the non-neoplastic hepatocytes, the cellular p62 content was unambiguously reduced in all malignant cells. The extent of decrease of p62 corresponded to the grade of histological differentiation of HCC cells (P<0.001). Using a semiquantitative scoring system, the median of p62 expression, which was 2.1 for normal hepatocytes, was significantly reduced to 1.2 for G1, 1.0 for G2, and 0.2 for G3 HCCs. These data suggest that neoplastic transformation is associated with a reduced p62 content. [ABSTRACT FROM AUTHOR]

Often, tumour cells acquire drug resistance phenotypes, which include the classical multidrug resistance (MDR) phenomenon accompanied by the synthesis of the P-glycoprotein (Pgp) and atypical MDR phenotypes mediated by different, in part unknown, mechanisms. To investigate the susceptibility of tumour cells exhibiting different kinds of MDR to treatment with heat, the hyperthermic survival of established human gastric and pancreatic carcinoma cell lines were studied and sublines exhibiting a classical and an atypical MDR phenotype were derived, respectively. Arrhenius analysis of this panel of gastrointestinal tumour cells revealed that both the classical and the atypical MDR variants exhibited no breaking points (T*) in contrast to the parent tumour cells. The activation enthalpies E[sub A] were about 40% lower at T > T* in comparison to the E[sub A] at lower temperatures. Classical MDR variants of both gastrointestinal tumour cell types exhibited a similar E[sub A] value, whereas the E[sub A] of atypical MDR gastric carcinoma cells was 1.6-fold higher than the E[sub A] of corresponding pancreatic carcinoma cells. In comparison to the parent lines, the drug resistant variants exhibited a 2.1-fold (gastric carcinoma, classical MDR), 2.7-fold (gastric carcinoma, atypical MDR) and 1.4-fold (pancreatic carcinoma, classical MDR) increase of activation enthalpies and a nearby unchanged E[sub A] in pancreatic carcinoma cells exhibiting an atypical MDR. [ABSTRACT FROM AUTHOR]

The role of DNA topoisomerases (Topo) IIα and IIβ was investigated in various drug-resistant melanoma cells. Melanoma cells resistant to etoposide, exhibited an up to tenfold reduced Topo II activity corresponding to an increasing degree of drug resistance indicating that modulation of Topo II activity contribute to the drug-resistant phenotype. The reduction of Topo II activity was reflected by decreased nuclear amounts of both Topo II isoforms. [ABSTRACT FROM AUTHOR]

Background: Human cancer cell lines grown in the presence of the cytotoxic agent mitoxantrone frequently develop resistance associated with a reduction in intracellular drug accumulation without increased expression of the known drug resistance transporters P-glycoprotein and multidrug resistance protein (also known as multidrug resistance-associated protein). Breast cancer resistance protein (BCRP) is a recently described adenosine triphosphate-binding cassette transporter associated with resistance to mitoxantrone and anthracyclines. This study was undertaken to test the prevalence of BCRP overexpression in cell lines selected for growth in the presence of mitoxantrone.Methods: Total cellular RNA or poly A+ RNA and genomic DNA were isolated from parental and drug-selected cell lines. Expression of BCRP messenger RNA (mRNA) and amplification of the BCRP gene were analyzed by northern and Southern blot hybridization, respectively.Results: A variety of drug-resistant human cancer cell lines derived by selection with mitoxantrone markedly overexpressed BCRP mRNA; these cell lines included sublines of human breast carcinoma (MCF-7), colon carcinoma (S1 and HT29), gastric carcinoma (EPG85-257), fibrosarcoma (EPF86-079), and myeloma (8226) origins. Analysis of genomic DNA from BCRP-overexpressing MCF-7/MX cells demonstrated that the BCRP gene was also amplified in these cells.Conclusions: Overexpression of BCRP mRNA is frequently observed in multidrug-resistant cell lines selected with mitoxantrone, suggesting that BCRP is likely to be a major cellular defense mechanism elicited in response to exposure to this drug. It is likely that BCRP is the putative "mitoxantrone transporter" hypothesized to be present in these cell lines. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article concerning the significance of S100P expression in ovarian cancers.

Manufacture of high performance uncooled 1300 nm distributed feed-back (DFB) lasers operating single mode over the −40 to +85°C range requires control of the wavelength variation across a 2″ wafer to less than 10nm and preservation of grating definition during processing and regrowth. We have used atmospheric pressure metalorganic vapor phase epitaxy, without substrate rotation to achieve the necessary uniformity. Material was assessed using photoluminescence, x-ray diffraction, transmission electron microscopy, electrochemical current/voltage profiling, and secondary ion mass spectroscopy. The devices are based on a strained quantum well structure with an n-type grating layer to provide gain coupling. The best result gave a wavelength spread across 32×32 mm center square of a 2″ InP wafer of 3 nm. Buried heterostructure DFBs manufactured with high yield in this way operate from −40 to +85°C, with thresholds at 85°C as low as 18 mA. [ABSTRACT FROM AUTHOR]

Investigates the electroluminescence (EL) properties of resonantly coupled gallium arsenide/aluminum arsenide superlattices (SL). Use of superconductor SL for tunneling structures; Demonstration of higher subbands in SL by resonant tunneling; Insights on the light emitting mechanism of SL.

Measures the nonlinearity of the excitonic absorption in isolated indium arsenide quantum wells inserted in a gallium arsenide matrix. Observation of absorption changes; Determination of the saturation intensity; Calculation of the nonlinear absorption cross section.

A novel unipolar transistor device has been realized starting from two-dimensional electron systems (2DES) in modulation-doped AlGaAs/GaAs heterostructures. A 600-nm-wide 1D channel is insulated laterally from 2DES regimes by 700-nm-wide deep mesa etched trenches. The conductivity in the quasi-one-dimensional channel can be tuned via the in-plane lateral field effect of the adjacent 2DES gates where the vacuum (or air) in the etched trenches serves as the dielectric. Room-temperature operation is demonstrated yielding a 17 μS transconductance corresponding to 170 mS/mm 2D transconductance. [ABSTRACT FROM AUTHOR]