Optical measurement and control of spin diffusion in n-doped GaAs quantum wells

Transient spin gratings are used to study spin diffusion in lightly n-doped GaAs quantum wells at low temperatures. The spin grating is shown to form in the excess electrons from doping, providing spin relaxation and transport properties of the carriers most relevant to spintronic applications. We demonstrate that spin diffusion of the these carriers is accelerated by increasing the density or energy of the optically excited carriers. These results can be used to better understand and even control spin transport in experiments that optically excite spin-polarized carriers.

A prospective, blinded analysis of thymidylate synthase and p53 expression as prognostic markers in the adjuvant treatment of colorectal cancer

BACKGROUND

Despite previous studies, uncertainty has persisted about the role of thymidylate synthase (TS) and p53 status as markers of prognosis in colorectal cancer (CRC).

PATIENTS AND METHODS

A total of 967 patients accrued to a large adjuvant trial in CRC were included in a prospectively planned molecular substudy, and of them, 59% had rectal cancer and about 90% received adjuvant chemotherapy (either systemically or randomly allocated to intraportal 5-fluorouracil infusion or both). TS and p53 status were determined, blinded to any clinical data, by immunohistochemistry using a validated polyclonal antibody or the DO-7 clone, respectively, and their relationships with overall survival were examined.

RESULTS

High TS expression was observed in 58% and overexpression of p53 in 60% of tumours. TS expression correlated with tumour stage, and p53 overexpression, with rectal cancers. There was no evidence that either marker was significantly associated with survival by either univariate (TS hazard ratio (HR) = 0.94, 95% CI 0.76-1.18 and P = 0.6 and p53 HR = 0.98, 95% CI 0.78-1.23 and P = 0.9) or multivariate analyses (TS HR = 0.99, 95% CI 0.79-1.25 and P = 0.9 and p53 HR = 0.98, 95% CI 0.78-1.23 and P = 0.8).

CONCLUSIONS

Neither TS nor p53 expression has significant prognostic value in the adjuvant setting of CRC.

Humanized transgenic mice expressing HLA DR4-DQ3 haplotype: reconstitution of phenotype and HLA-restricted T-cell responses

Many autoimmune conditions have close genetic linkages to particular human histocompatibility leukocyte antigen (HLA) class II genes. With the aim of establishing a murine model of autoimmune disease, we have generated an HLA DR4-DQ3 haplotype transgenic (Tg) mouse that expresses a 440-kb yeast artificial chromosome harbouring DRA, DRB1*040101, DRB4*010301, DQA1*030101, DQB1*0302 and all the internal regulatory segments. This Tg mouse line was crossed to human CD4 (hCD4) Tg mice and endogenous class II knockout mice (I-A(o/o) and I-E(o/o)) lines to generate a DR4-DQ3.hCD4.IAE(o/o) Tg line. The Tg DR and DQ molecules are expressed on the physiological cell types in these animals, i.e. on most B cells (>85%), dendritic cells (DCs) and macrophages but not on T cells, with levels of expression comparable with those of human B cells (where DR > DQ expression). The DR4/DQ3 transgenes fully reconstituted the CD4 T-cell compartment, in both the thymus and the periphery, and the analysis of the T-cell receptor repertoire in the Tg mice confirmed that these class II molecules were able to mediate thymic selection of a broad range of Vbeta families. HLA DR4- and DQ3-restricted T-cell responses were elicited following immunization with known T-cell determinants presented by these molecules. Furthermore, the DR4-DQ3-restricted CD4(+) T cells conferred protective antibody-mediated immunity against an otherwise lethal infection with Salmonella enterica var. typhimurium. These new DR4-DQ3 Tg mice should prove to be valuable tools for dissecting the importance of this class II haplotype in autoimmune disorders like rheumatoid arthritis.

A phase II randomized controlled trial of a novel male contraception, an intra-vas device

The aim of this study was to introduce a novel male contraceptive method, an intra-vas device (IVD), and to assess the efficacy, safety and satisfaction of recipients compared with no-scalpel vasectomy (NSV). A phase II randomized controlled trial was conducted in China in 2003. Two hundred and eighty-eight male subjects seeking vasectomy were randomly assigned to the IVD or NSV group. Follow up included a telephone questionnaire on the 14th postoperative day and visits at the third and 12th postoperative months. The follow-up rates at the three time points were 100%, 100% and 96.5% respectively. There was no technical failure in any subject. The surgical conditions were similar in both groups, but the IVD group experienced an additional 5 min of operative time (p<0.001). The IVD group recovered normal activity and sexual intercourse more rapidly (both p<0.05). The azoospermia rate was lower in the IVD group than in the NSV group at the third and 12th postoperative months. The rate of contraceptive success based on semen analyses was similar in both groups, especially at the 12th postoperative month (94.3% in the IVD group vs. 98.6% in the NSV group; p=0.054). The IVD group had less risk of complications (i.e. pain, congestive epididymitis and sperm granuloma). More subjects reported satisfaction with IVD sterilization than with NSV. The two procedures were similar in terms of surgical complications. The IVD was slightly less effective, but had a lower risk of later adverse events than the NSV technique. The IVD group also reported a higher level of satisfaction.

An apparatus for studying the response of cultured endothelial cells to stresses

In order to simulate the hemodynamic environment of human arteries in vivo, we designed a laminar flow apparatus which can precisely simulate the normal stress and shear stress to which cultured endothelial cells are exposed. Under both normal and abnormal physiological conditions, this apparatus can accurately control and adjust the values of normal stress and shear stress and the frequency of pulse waves, as well as the amplitude of pulsatile flow. This in vitro apparatus provides an experimental platform for studying the response of the biological characteristics of cultured endothelial cells in a hemodynamic environment.

Antisense Smo under the control of the PTCH1 promoter delivered by an adenoviral vector inhibits the growth of human pancreatic cancer

Hedgehog (Hh) signaling pathway is crucial in growth and patterning during embryonic development. Recent data have shown an association of its activation with cancer formation and maintenance. A ligand-dependent activation, where Hh components (SHH, PTCH1, Smo and GLi1) are aberrantly expressed with PTCH1 being a negative feedback regulator, is a newly identified mechanism for pancreatic carcinogenesis. In this study, we developed a cell-specific cytotoxic model for the treatment of human pancreatic cancer (HPC) in which expression of antisense Smo (SAS) was under the control of the PTCH1 promoter (ptch/p) delivered by an adenoviral vector (Ad-ptch/p-SAS). We observed that the cell-specific cytotoxicity in HPC cells depended on the expressions of inherent PTCH1, Smo and GLi1 in the target cells in which the Hh pathway was presumed to be activated. Fluorescence-activated cell sorting analysis indicated that the cell death was apoptosis. Western blot showed that Smo protein in the infected cells significantly decreased. Furthermore, an in vivo experiment demonstrated that such Hh activity-cell-specific cytotoxicity was achieved by daily intratumoral injection of Ad-ptch/p-SAS (10(9) plaque-forming unit) for 5 days. Our study suggests that targeting at the Hh signaling pathway may be an effective novel gene therapeutic strategy alone or in combination with other agents for the treatment of pancreatic cancer.

Biomarkers detected by proteomic analysis predicts breast cancer response to neoadjuvant chemotherapy

669

Background: Neoadjuvant chemotherapy provides an excellent opportunity for objective assessment of treatment-induced tumor response and for studying biomarkers characteristic of therapy-induced tumor responses. Methods: Proteomic analysis of T3/T4 breast cancer was performed in patients with locally advanced breast cancer in a phase II clinical trial. The breast cancer specimen was obtained before and after four cycles of Taxotere/Carboplatin/±Herceptin treatment. Two proteomic approaches, SELDI mass spectrometry and Clontech Ab Microarray 500, were used to screen for protein biomarkers that predict response of breast cancer to chemotherapy. Results: Five tumors with pathologically complete response (pCR) and 29 tumors with various amounts of residual tumors (Non-pCR) were analyzed by SELDI-TOF using the NP 20 chip. The normalized mass signals were compared between pCR vs Non-pCR at each aligned location by Wilcoxon rank sum test. Statistically significant differences were found at 22 m/z locations using a liberal p <0.20 criterion. The best univariate predictor occurred at m/z 14960 (p=0.004), which correctly classified 5/5 pCR spectra (100%) and 24/29 Non-pCR spectra (83%). A multivariate classification tree developed using m/z 14960 and m/z 12138 intensities correctly classified all 34 spectra. Ab microarray analysis was performed on five pCR tumors and in five tumors with the largest residual cancer. The Internal Normalization Ratio (INR) was calculated and used to compare the difference of protein expression between the two groups. Eight differentially expressed protein biomarkers were selected with the criteria of a statistically significant (Student t, p<0.05) expression change of <0.77 or >1.3 fold. Three proteins (Tat-SF1, PYK2 and PTP1B) were higher, and five (E2F2, IL1b, FEN1, CDC37 and ACM1) were lower in tumors with pCR. The unsupervised hierarchical clustering of the 10 samples by these eight proteins completely separated the pCR tumors from the poor responders. Conclusions: Our study suggests that bothSELDImass spectrometry and antibody microarray may be used to predict the tumor response to neoadjuvant chemotherapy. Proteomic analysis may be useful in developing tailored chemotherapy for breast cancer.

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Solid organ second malignant neoplasms among children diagnosed with malignant bone tumors treated on Children Cancer Study Group/Pediatric Oncology Group protocols after 1980

9007

Background: The growing number of individuals surviving childhood cancer has increased the awareness and recognition of long-term sequelae. One of the most worrisome complications following cancer therapy is the development of second malignant neoplasms (SMN), in particular, late-occurring solid second malignancies related radiation therapy. Methods: We describe the incidence of solid organ SMN in survivors of pediatric malignant bone tumors (MBT) treated on legacy CCG/POG protocols from 1980 to 2005. This retrospective cohort study included 2,842 patients, 1,686 treated for osteosarcoma (OS) and 1,156 treated for Ewings Sarcoma (ES). The cohort included 56% males and 44% females, with a median age at primary diagnosis of 13 years. The median length of follow-up was 4.3 years (range: 0 to 20.9 years). Results: At the time of the analysis, 64% of patients in this study are alive. Seventeen patients with solid organ SMN were identified, and included three patients with breast cancer, three with malignant fibrous histiocytoma, two with osteosarcoma, and 9 patients with other solid organ malignancies. The standardized incidence ratio (SIR=observed/expected cases) was 2.9 (95% confidence interval [CI], 1.4–5.4) for patients treated for OS and 5.0 (95%CI 2.6–9.4) for patients treated for ES. The median time from diagnosis to develop solid organ SMN was 7 years (range: 1 to 13 years). The 10-year cumulative incidence of solid organ SMN for the entire cohort was 1% (95%CI 0.6–2%). In univariate analysis, treatment with etoposide, cyclophosphamide or radiotherapy were each associated with a higher than expected incidence of cancer with SIR of 4.8 (95% CI, 2.5–9.5), 5.8 (95% CI, 3.5–9.5) and 4.1 (95% CI, 2.4–7.1), respectively. Conclusions: Solid organ SMNs are rare after treatment for OS and ES, although higher in patients treated for ES. Recurrence remains the most significant problem for patients diagnosed with MBT and development of improved therapies with fewer long-term consequences remains paramount. However, solid organ cancers are likely to increase with longer follow-up. Therefore, surveillance should focus on monitoring for both recurrence of primary malignancies and development of SMN.

No significant financial relationships to disclose.

Clinical, signaling pathway, and cellular effects of epidermal growth factor receptor (EGFR) inhibition with gefitinib in combination with paclitaxel and radiation in patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN)

15540

Background: EGFR, overexpressed in >90% of SCCHN, activates pathways that modulate proliferation, apoptosis, and therapeutic resistance. We examined the clinical, signaling, and cellular effects of EGFR inhibition in serial tumor biopsies in patients (Pts.) with locally advanced SCCHN receiving the EGFR-inhibitor gefitinib (GEF) in combination with paclitaxel (PTX) and radiation (XRT). Methods: Phase I dose-escalation study of concurrent GEF 250 mg with weekly PTX 45mg/m2 x 6 doses and XRT to 72Gy. Eligiblity: SCCHN, Stage III-IVB, age ≥18 yr., no prior XRT or chemotherapy, ECOG ≤2, adequate organ function and informed consent. Endpoints include determination of maximum tolerated dose (MTD) and immunostaining of tumor pre- and post-treatment for expression of phospho-EGFR, Akt, Erk1/2, STAT3, NF-κB p65, Ki67, and TUNEL, and measurement of serum IL-6, IL-8, VEGF, HGF and GROα to assess the functional effects of EGFR-inhibition. Results: Four Pts., median age 63 yr. (range 41–83), 3 men, 1 woman were treated. Aspiration pneumonia and interstitial pneumonitis were each observed in 1 Pt and prolonged Grade 3/4 mucositis in all 4 Pts. Three Pts achieved a CR, with one Pt requiring neck dissection to remove a residual node. One Pt had a local CR but rapidly developed pulmonary metastasis. One Pt. exhibited decreased staining of all signaling phosphoproteins and Ki67 with increased TUNEL staining. Decrease or increase in IL-8, VEGF and HGF at one month corresponded with response or progression in two patients. Conclusions: Pulmonary complications and prolonged mucositis were dose-limiting. EGFR inhibition affects downstream signaling, cell survival and serum factors in a subset of patients.

No significant financial relationships to disclose.

Eriocalyxin B induces apoptosis of t(8;21) leukemia cells through NF-κB and MAPK signaling pathways and triggers degradation of AML1-ETO oncoprotein in a caspase-3-dependent manner

Diterpenoids isolated from Labiatae family herbs have strong antitumor activities with low toxicity. In this study, Eriocalyxin B (EriB), a diterpenoid extracted from Isodon eriocalyx, was tested on human leukemia/lymphoma cells and murine leukemia models. Acute myeloid leukemia cell line Kasumi-1 was most sensitive to EriB. Significant apoptosis was observed, concomitant with Bcl-2/Bcl-XL downregulation, mitochondrial instability and caspase-3 activation. AML1-ETO oncoprotein was degraded in parallel to caspase-3 activation. EriB-mediated apoptosis was associated with NF-kappaB inactivation by preventing NF-kappaB nuclear translocation and inducing IkappaBalpha cleavage, and disturbance of MAPK pathway by downregulating ERK1/2 phosphorylation and activating AP-1. Without affecting normal hematopoietic progenitor cells proliferation, EriB was effective on primary t(8;21) leukemia blasts and caused AML1-ETO degradation. In murine t(8;21) leukemia models, EriB remarkably prolonged the survival time or decreased the xenograft tumor size. Together, EriB might be a potential treatment for t(8;21) leukemia by targeting AML1-ETO oncoprotein and activating apoptosis pathways.

Segmental uniparental isodisomy on 5q32-qter in a patient with childhood-onset schizophrenia

Schizophrenia is a severe mental disorder affecting approximately 1% of the world's population. Although the aetiology of schizophrenia is complex and multifactorial, with estimated heritabilities as high as 80%, genetic factors are the most compelling. Childhood-onset schizophrenia (COS), defined as onset of schizophrenia before the age of 13 years, is a rare and malignant form of the illness that may have more salient genetic influence. The first known case of paternal segmental uniparental isodisomy (iUPD) on 5q32-qter in a patient with COS is described, which adds to the previously known high rates of chromosomal abnormalities reported in this sample. iUPD is a rare genetic condition in which the offspring receives two chromosomal homologues from one parent. Segmental UPD is defined as UPD on a portion of a chromosome with biparental inheritance seen in the rest of the homologous pair. Complications owing to this abnormality may arise from malfunctioning imprinted genes or homozygosity of recessive disease-causing mutations. This aberration became apparent during whole-genomic screening of a COS cohort and is of particular interest because 5q has been implicated in schizophrenia by several genomewide linkage studies and positive gene associations. This report, therefore, presents more evidence that schizophrenia susceptibility gene, or genes, may be found on distal 5q.