Observation and understanding of anisotropic strain relaxation in selectively grown SiGe fin structures

The performance of heterogeneous 3D transistor structures critically depends on the composition and strain state of the buffer, channel and source/drain regions. In this paper we used an in-line high resolution x-ray diffraction (HRXRD) tool to study in detail the composition and strain in selectively grown SiGe/Ge fin structures with widths down to 20 nm. For this purpose we arranged fins of identical dimensions into larger arrays which were then analyzed using an x-ray beam several tens of micrometers in size. Asymmetric reciprocal space maps measured both parallel and perpendicular to the fins allowed us to extract the lattice parameters in all three spatial directions. Our results demonstrate an anisotropic in-plane strain state of the selectively grown SiGe buffer in case of narrower fins with significantly reduced relaxation in the direction along the fin. This observation was verified using nano-beam electron diffraction, and is explained based on the reduced probability for dislocation half-loops to evolve in trenches narrower than a few times the critical radius. Moreover, we introduce and discuss in detail a methodology for the determination of the composition in case of an anisotropic in-plane strain state which differs from the procedure commonly used for blanket layers. Our findings verify the importance of in-line HRXRD measurements for process development and monitoring as well as the fundamental study of relaxation and defect formation in confined volumes.

Synergistic inhibition of breast cancer cell lines with the combination of a dual inhibitor of EGFR/HER-2/neu and a Bcl-2 inhibitor

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Background: The epidermal growth factor receptor (EGFR; ErbB1) and HER-2/neu (ErbB2), members of the ErbB family of receptor tyrosine kinases, are overexpressed in a variety of human tumors and overexpression generally correlates with poor prognosis and decreased survival. Use of inhibitors of these receptors as monotherapies, e.g., trastuzumab, Iressa, and erlotinib, has led to advances in treatment, but many patients do not respond or develop resistance. The anti-apoptotic protein, Bcl-2, is also overexpressed in a number of human tumors. Inhibitors of Bcl-2 induce apoptosis and sensitize cancer cells to other therapies. This study assesses the effects of a combination of a reversible inhibitor of both EGFR and HER-2/neu that is similar to lapatinib (GW2974) and a pan inhibitor of the Bcl-2 family (GX15–070: Gemin X Biotechnologies, Inc.) on the growth of human breast cancer cells. Methods: The MCF-7 human breast cancer cell line transfected with a control vector, MCF/neo, and the HER-2/neu transfected MCF-7 cell line, MCF/18, were treated with various concentrations of GW2974 (0.25–10 μM) and/or the GX15–070 pan Bcl-2 inhibitor (50–500 nM). After a 3 day exposure, cell number was determined using the colorimetric MTT tetrazolium dye assay. Percent of control was normalized to corresponding concentrations of the solvent for both agents (DMSO). Results: Treatment with the GW2974 dual inhibitor or the GX15–070 pan Bcl-2 inhibitor resulted in dose-dependent growth inhibition in both the control and HER-2/neu transfected MCF-7 cell lines. The combination of both agents produced synergistic growth inhibition in both cell lines as confirmed by isobologram analysis. Conclusions: This study has demonstrated synergy with the combination of a dual inhibitor of EGFR and HER-2/neu and an inhibitor of Bcl-2 in control and HER-2/neu overexpressing MCF-7 human breast cancer cells. This finding warrants an evaluation of this combination in clinical trials for the treatment of patients with metastatic breast cancer.

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Exercise diminishes the activity of acetyl-CoA carboxylase in human muscle

Studies in rats suggest that increases in fatty acid oxidation in skeletal muscle during exercise are related to the phosphorylation and inhibition of acetyl-CoA carboxylase (ACC), and secondary to this, a decrease in the concentration of malonyl-CoA. Studies in human muscle have not revealed a consistent decrease in the concentration of malonyl-CoA during exercise; however, measurements of ACC activity have not been reported. Thus, whether the same mechanism operates in human muscle in response to physical activity remains uncertain. To investigate this question, ACC was immunoprecipitated from muscle of human volunteers and its activity assayed in the same individual at rest and after one-legged knee-extensor exercise at 60, 85, and 100% of knee extensor VO2max. ACC activity was diminished by 50-75% during exercise with the magnitude of the decrease generally paralleling exercise intensity. Treatment of the immunoprecipitated enzyme with protein phosphatase 2A restored activity to resting values, suggesting the decrease in activity was due to phosphorylation. The measurement of malonyl-CoA in the muscles revealed that its concentration is 1/10 of that in rats, and that it is diminished (12-17%) during the higher-intensity exercises. The respiratory exchange ratio increased with increasing exercise intensity from 0.84 +/- 0.02 at 60% to 0.99 0.04 at 100% VO2max. Calculated rates of whole-body fatty acid oxidation were 121 mg/min at rest and 258 +/- 35, 264 +/- 63, and 174 +/- 76 mg/min at 60, 85, and 100% VO2max, respectively. The results show that ACC activity, and to a lesser extent malonyl-CoA concentration, in human skeletal muscle decrease during exercise. Although these changes may contribute to the increases in fat oxidation from rest to exercise, they do not appear to explain the shift from mixed fuel to predominantly carbohydrate utilization when exercise intensity is increased.

Antisense oligonucleotides to the epidermal growth factor receptor

Overexpression of the epidermal growth factor receptor (EGFR) has been observed in human breast tumors and is associated with poor prognosis in breast cancer patients. This would suggest that blocking the activity of the EGFR is a logical approach in the treatment of breast cancer. Three 20-mer phosphorothioate oligodeoxynucleotides were designed to target different regions of the human epidermal growth factor receptor (EGFR) mRNA. Several analogs of these oligodeoxynucleotides (the 2'-fluoro analog, the 2'-propoxy analog, and/or the 5-methyl cytosine analog) were also evaluated. We added these compounds to a human ovarian carcinoma cell line (SKOV3) and a human lung carcinoma line (A549), both of which overexpress the EGFR. All of these antisense oligonucleotides inhibited expression of the 10 kb EGFR mRNA (range: 22-97% inhibition) compared to a scrambled control oligonucleotide or an untreated control. Expression of the less prominent 5.6 kb EGFR mRNA band was also inhibited by all but two of the parent oligonucleotides. No inhibition of this 5.6 kb band was found with the control oligonucleotide. The reduction in the expression of EGFR mRNA by the three most potent antisense compounds was accompanied by a significant reduction of EGFR protein (90-98%) and in vitro growth inhibition of SKOV3 cells as compared to the control oligonucleotide.

Protein tyrosine kinase activity in breast cancer and its relation to prognostic indicators

Tyrosine kinase dependent oncogenes and growth factor receptors are of prognostic importance in breast cancer, but the relation of cytosolic protein tyrosine kinase (PTK) activity to traditional prognostic indicators is poorly defined. We determined cytosolic PTK activity in tumor extracts of 61 women with invasive breast cancer, including 51 primary specimens and 12 nodal or metastatic specimens, 7 women with in situ breast cancer, and 8 control breast specimens. PTK activity (pmol/min/mg) was measured in a dot blot assay using phosphotyrosine antibodies to detect phosphorylated tyrosyl residues in the tissue extracts. Compared with control specimens (mean PTK = 20.5), tyrosine kinase activity was significantly greater in invasive primary cancers (mean PTK = 298.1; p = 0.0008), and nodal/metastatic specimens (mean PTK = 491.5; p = 0.0009). PTK levels of invasive cancers did not correlate with age (p = 0.36), tumor size (p = 0.83), nodal status (p = 0.37), estrogen receptor status (p = 0.66), or progesterone receptor status (p = 0.09). Thus, while tyrosine kinase activity is increased in breast cancer, correlations with traditional prognostic indicators were not found.

Increased urinary excretion of pyridinium cross-links in cancer patients

Pyridinoline (PYD) and deoxypyridinoline (DPD), two collagen-based cross-links found in bone, were measured by high-performance liquid chromatography in urine samples from 65 control subjects and 97 patients with either untreated or progressive cancer. Patients with cancer had significantly (P < 0.001) higher urine concentrations of PYD and DPD than did control subjects. Both cross-links were increased in cancer patients with and without clinically detectable bone metastases, although patients with bone and liver involvement had higher mean concentrations. The mean concentrations of both cross-links were also significantly higher in the urine samples of inpatients than in an outpatient ambulatory population. These findings suggest that the measurement of PYD and DPD in urine may be useful in assessing bone metastases and bone resorption in cancer patients.

Increased urinary excretion of pyridinium cross-links in cancer patients

Pyridinoline (PYD) and deoxypyridinoline (DPD), two collagen-based cross-links found in bone, were measured by high-performance liquid chromatography in urine samples from 65 control subjects and 97 patients with either untreated or progressive cancer. Patients with cancer had significantly (P &lt; 0.001) higher urine concentrations of PYD and DPD than did control subjects. Both cross-links were increased in cancer patients with and without clinically detectable bone metastases, although patients with bone and liver involvement had higher mean concentrations. The mean concentrations of both cross-links were also significantly higher in the urine samples of inpatients than in an outpatient ambulatory population. These findings suggest that the measurement of PYD and DPD in urine may be useful in assessing bone metastases and bone resorption in cancer patients.

The protein phosphatases involved in cellular regulation. 3. Fatty acid synthesis, cholesterol synthesis and glycolysis/gluconeogenesis

The nature of the protein phosphatases involved in the regulation of glycolysis/gluconeogenesis, fatty acid synthesis and cholesterol synthesis in rat liver has been investigated using L-pyruvate kinase, ATP-citrate lyase, acetyl-CoA carboxylase and hydroxymethylglutaryl-CoA reductase as substrates. The results show that protein phosphatases-1, 2A and 2C are the only significant protein phosphatases in rat liver acting on these four substrates. The relationship of these three enzymes to other protein phosphatases described in the literature is discussed.