Mapping resting-state functional connectivity using perfusion MRI

Resting-state, low-frequency (<0.08 Hz) fluctuations of blood oxygenation level-dependent (BOLD) magnetic resonance signal have been shown to exhibit high correlation among functionally connected regions. However, correlations of cerebral blood flow (CBF) fluctuations during the resting state have not been extensively studied. The main challenges of using arterial spin labeling perfusion magnetic resonance imaging to detect CBF fluctuations are low sensitivity, low temporal resolution, and contamination from BOLD. This work demonstrates CBF-based quantitative functional connectivity mapping by combining continuous arterial spin labeling (CASL) with a neck labeling coil and a multi-channel receiver coil to achieve high perfusion sensitivity. In order to reduce BOLD contamination, the CBF signal was extracted from the CASL signal time course by high frequency filtering. This processing strategy is compatible with sinc interpolation for reducing the timing mismatch between control and label images and has the flexibility of choosing an optimal filter cutoff frequency to minimize BOLD fluctuations. Most subjects studied showed high CBF correlation in bilateral sensorimotor areas with good suppression of BOLD contamination. Root-mean-square CBF fluctuation contributing to bilateral correlation was estimated to be 29+/-19% (N=13) of the baseline perfusion, while BOLD fluctuation was 0.26+/-0.14% of the mean intensity (at 3 T and 12.5 ms echo time).     

Evaluation of the prognostic significance of androgen receptor expression in metastatic breast cancer

The purpose of this study was to investigate the influence of androgen receptor (AR) expression in tumour tissue on survival of patients with metastatic breast cancer. Tumour specimens from 232 patients with metastatic breast cancer were examined for presence of AR by immunohistochemistry. According to the extent of immunostaining, AR expression was classified as score 0, 1+, 2+, or 3+. AR positivity was observed in 164 (70.7%) tumours. The median survival after disease recurrence (SAR) of patients with AR-expressing tumours was significantly longer compared to that of patients with AR-negative tumours (21.89 months, 95% CI 17.23–26.55 vs 11.99 months, 95% CI 9.36–14.62; log-rank test 0.0282). In addition, patients with AR score 3+ had a significantly longer disease-free survival (DFS) compared to patients with AR score 0, 1+, and 2+, (24.67 months, 95% CI 13.72–35.62 vs 16.36 months, 95% CI 13.18–19.54, log-rank test 0.0043). Multivariate Cox analyses showed no statistically significant influence of AR expression on DFS or SAR. In conclusion, SAR is significantly longer in patients with AR-expressing breast carcinoma. However, AR expression is not an independent prognostic factor for SAR in metastatic breast cancer.     

The Functional Polymorphism of Erythropoietin Gene rs1617640 G>T Is Not Associated with Susceptibility and Clinical Outcome of Early-stage Breast Cancer

Recent data suggest that erythropoietin (EPO) plays a substantial role in cancer development and clinical outcome by stimulating cell proliferation, invasion and angiogenesis. A functional polymorphism (rs1617640 G>T) in the promoter region of the EPO gene increases EPO protein expression. In the present study, we investigated the association of EPO rs1617640 G>T with susceptibility and clinical outcome of early-stage breast cancer. Genomic DNA of 539 female patients with histologically confirmed early-stage breast cancer and 804 controls was genotyped for EPO rs1617640 G>T. No association was found between EPO rs1617640 G>T and early-stage breast cancer susceptibility and clinical outcome (hazard ratio=1.24, 95% confidence interval=1.82-1.90, p=0.31). In conclusion, our findings suggest a lack of influence of EPO rs1617640 G>T on early-stage breast carcinogenesis and clinical outcome.     

fMRI of the temporal lobe of the awake monkey at 7 T

Increasingly 7 T scanners are used for fMRI of humans and non-human primates, promising improvements in signal-to-noise, spatial resolution and specificity. A disadvantage of fMRI at 7 T, but already at 3 T, is that susceptibility artifacts from air-filled cavities like the ear canal and nasal cavity cause signal loss and distortion. This limits the applicability of fMRI in these areas, thereby limiting study of these areas, but it also limits study of processes that span large-scale cortical networks or the entire brain. Our goal is to study the inferior temporal (IT) lobe in awake monkeys because of its importance in object perception and recognition, but the functional signal is degraded by strong susceptibility gradients. To allow fMRI of this region, we used an optimized SE-EPI, which recovers signal lost with GE-EPI and we corrected for susceptibility-induced image distortion. SE-EPI has the added advantage that, in contrast to GE-EPI, where the functional signal derives to a large extent from veins, the SE-EPI signal arises from the microvasculature, and hence it better represents the neural activation. We show fMRI at 7 T of the entire visual pathway in the awake primate with robust and widespread activation in all ventral areas of the brain, including areas adjacent to the ear canal. This allows fMRI of areas that normally suffer from artifact and thus more reliable whole-brain studies.     

Asymptomatic primary malignant melanoma of the esophagus

BACKGROUND: Primary malignant melanoma of the esophagus is an exceedingly rare disease. This tumor is typically aggressive and disseminates early via the lymphatics and the bloodstream with a mean survival time between 10 and 15 months after radical surgical resection. The role of chemotherapy and immunotherapy is unclear. No treatment plan for the disease has yet been established. CASE REPORT: A 78-year-old man came for a checkup with a medical history of reflux esophagitis and chronic gastritis. Esophagogastroscopy showed a bluishgray tumor of the esophagus, and histology revealed features consistent with malignant melanoma. The patient underwent total transhiatal esophagectomy with curative intention, and esophagogastric anastomosis was performed. Immunohistochemistry revealed tumor cells strongly positive for the melanoma-specific antigen HMB45 and protein S-100, and negative for cytokeratin. A proposed postoperative chemotherapy was declined by the patient. Nine months after surgery, the patient's condition deteriorated, and a mediastinal lymph node conglomerate was found. Two months later, he died of bleeding into the cervical soft tissue. CONCLUSION: Up to date, radical surgical resection is the main treatment. Very little is known about the benefits of chemotherapy and immunotherapy. However, these therapeutic modalities may play an important role in the future.     

The role of the Angiopoietins in vascular morphogenesis

The Angiopoietin/Tie system acts as a vascular specific ligand/receptor system to control endothelial cell survival and vascular maturation. The Angiopoietin family includes four ligands (Angiopoietin-1, Angiopoietin-2 and Angiopoietin-3/4) and two corresponding tyrosine kinase receptors (Tie1 and Tie2). Ang-1 and Ang-2 are specific ligands of Tie2 binding the receptor with similar affinity. Tie2 activation promotes vessel assembly and maturation by mediating survival signals for endothelial cells and regulating the recruitment of mural cells. Ang-1 acts in a paracrine agonistic manner inducing Tie2 phosphorylation and subsequent vessel stabilization. In contrast, Ang-2 is produced by endothelial cells and acts as an autocrine antagonist of Ang-1-mediated Tie2 activation. Ang-2 thereby primes the vascular endothelium to exogenous cytokines and induces vascular destabilization at higher concentrations. Ang-2 is strongly expressed in the vasculature of many tumors and it has been suggested that Ang-2 may act synergistically with other cytokines such as vascular endothelial growth factor to promote tumor-associated angiogenesis and tumor progression. The better mechanistic understanding of the Ang/Tie system is gradually paving the way toward the rationale exploitation of this vascular signaling system as a therapeutic target for neoplastic and non-neoplastic diseases.