Spin Hot Spots in vertically-coupled Few-electron Quantum Dots

The effects of spin-orbit (SO) coupling arising from the confinement potential in single and two vertically-coupled quantum dots have been investigated. Our work indicates that a dot containing a single electron shows the lifting of the degeneracy of dipole-allowed transitions at B=0 due to the SO coupling which disappears for a dot containing two electrons. For coupled dots with one electron in each dot, the optical spectra is not affected by the coupling and is the same as the dot containing one electron. However, for the case of two coupled dots where one partner dot has two interacting electrons while the other dot has only one electron, a remarkable effect is observed where the oscillator strength of two out of four dipole-allowed transition lines disappears as the distance between the dots is decreased

Xanthogranulomatous hypophysitis: a rare and often mistaken pituitary lesion.

Xanthogranulomatous hypophysitis (XGH) is a very rare form of pituitary hypophysitis that may present both clinically and radiologically as a neoplastic lesion. It may either be primary with an autoimmune aetiology and can occur in isolation or as a part of autoimmune systemic disease or secondary as a reactive degenerative response to an epithelial lesion (e.g. craniopharyngioma (CP), Rathke's cleft cyst, germinoma and pituitary adenomas) or as a part of a multiorgan systemic involvement such as tuberculosis, sarcoidosis or granulomatosis. It may also present with a variation of symptoms in children and adults. Our case series compares the paediatric and adult presentations of XGH and the differential diagnoses considered in one child and two adult patients, highlighting the wide spectrum of this condition. Endocrine investigations suggested panhypopituitarism in all three patients and imaging revealed a suprasellar mass compressing the optic chiasm suggestive of CP or Rathke's cleft cyst in one patient and non-functioning pituitary macroadenoma in two patients. Magnetic resonance imaging (MRI) demonstrated mixed signal intensities on T1- and T2-weighted sequences. Following endoscopic transsphenoidal surgery, histological analysis revealed necrotic material with a xanthogranulomatous reaction confirming XGH in two patients and a necrobiotic granulomatous chronic inflammatory infiltrate with neutrophils in one patient, which is not typical of current descriptions of this disorder. This case series describes the wide spectrum of XGH disease that is yet to be defined. Mixed signal intensities on T1- and T2-weighted MRI sequences may indicate XGH and diagnosis is confirmed by histology. Histological variation may indicate an underlying systemic process. LEARNING POINTS: XGH is a rare form of pituitary hypophysitis with a wide clinical and histological spectrum and can mimic a neoplastic lesion.XGH primarily presents with growth arrest in children and pubertal arrest in adolescents. In adults, the presentation may vary.A combination of hypopituitarism and mixed signal intensity lesion on MRI is suggestive of XGH and should be considered in the differential diagnosis of sellar lesions.Radical surgery is the treatment of choice and carries an excellent prognosis with no recurrence

Intracerebral Masson's Tumor—Slow-Filling Vascular Lesion Demonstrated by Indocyanine Green Video Angiography

BACKGROUND: Intravascular papillary endothelial hyperplasia or Massons's tumours are benign vascular lesions which are rarely seen intracranially. The vascular characteristics of these lesions are also unknown. CASE DESCRIPTION: We report a case of a 24 year old male patient with a 3 year history of headache and dizziness. Neuroradiological imaging showed a slow-growing lesion consistent with a low-grade glioma. Intra-operative appearance was of a vascular lesion which was slow-filling as demonstrated with indocyanine green video angiography. Histological analysis following resection revealed intravascular papillary endothelial hyperplasia (Masson's tumour). CONCLUSION: Masson's tumours are slow-filling vascular lesions. The pre-operative diagnosis of this lesion is difficult as it can mimic a neoplastic lesion. Conservative as well as surgical treatment options should therefore be carefully considered. Patients with subtotal resection must undergo long-term follow-up surveillance imaging as recurrence is a possibility

Cyclical vomiting syndrome secondary to a Chiari I malformation - a case report

Background: Cyclical vomiting syndrome is a disorder characterised by recurrent episodes of profuse vomiting. There are no cases in the literature on the management of children with presenting with cyclical vomiting syndrome and a Chiari malformation type I. Discussion: We report the case of a 12-year-old child diagnosed with cyclical vomiting syndrome and a Chiari malformation type I. The patient received symptomatic relief following a craniocervical decompression

Upregulated sirtuin 1 by miRNA-34a is required for smooth muscle cell differentiation from pluripotent stem cells

© 2015 Macmillan Publishers Limited. All rights reserved. microRNA-34a (miR-34a) and sirtuin 1 (SirT1) have been extensively studied in tumour biology and longevityaging, but little is known about their functional roles in smooth muscle cell (SMC) differentiation from pluripotent stem cells. Using well-established SMC differentiation models, we have demonstrated that miR-34a has an important role in SMC differentiation from murine and human embryonic stem cells. Surprisingly, deacetylase sirtuin 1 (SirT1), one of the top predicted targets, was positively regulated by miR-34a during SMC differentiation. Mechanistically, we demonstrated that miR-34a promoted differentiating stem cells' arrest at G0G1 phase and observed a significantly decreased incorporation of miR-34a and SirT1 RNA into Ago2-RISC complex upon SMC differentiation. Importantly, we have identified SirT1 as a transcriptional activator in the regulation of SMC gene programme. Finally, our data showed that SirT1 modulated the enrichment of H3K9 tri-methylation around the SMC gene-promoter regions. Taken together, our data reveal a specific regulatory pathway that miR-34a positively regulates its target gene SirT1 in a cellular context-dependent and sequence-specific manner and suggest a functional role for this pathway in SMC differentiation from stem cells in vitro and in vivo

A novel class of microRNA-recognition elements that function only within open reading frames.

MicroRNAs (miRNAs) are well known to target 3' untranslated regions (3' UTRs) in mRNAs, thereby silencing gene expression at the post-transcriptional level. Multiple reports have also indicated the ability of miRNAs to target protein-coding sequences (CDS); however, miRNAs have been generally believed to function through similar mechanisms regardless of the locations of their sites of action. Here, we report a class of miRNA-recognition elements (MREs) that function exclusively in CDS regions. Through functional and mechanistic characterization of these 'unusual' MREs, we demonstrate that CDS-targeted miRNAs require extensive base-pairing at the 3' side rather than the 5' seed; cause gene silencing in an Argonaute-dependent but GW182-independent manner; and repress translation by inducing transient ribosome stalling instead of mRNA destabilization. These findings reveal distinct mechanisms and functional consequences of miRNAs that target CDS versus the 3' UTR and suggest that CDS-targeted miRNAs may use a translational quality-control-related mechanism to regulate translation in mammalian cells

Cytotoxic drugs efficacy correlates with adipose tissue docosahexaenoic acid level in locally advanced breast carcinoma

Experimental studies indicated that long-chain polyunsaturated fatty acids may increase sensitivity of mammary tumours to several cytotoxic drugs. To evaluate this hypothesis in breast cancer, we have prospectively studied the association between levels of fatty acids stored in breast adipose tissue and the response of the tumour to chemotherapy in 56 patients with an initially localized breast carcinoma. Adipose breast tissue was obtained at the time of biopsy, and individual fatty acids were measured as a percentage of total fatty acids using capillary gas chromatography. Patients then received primary chemotherapy, combining mitoxantrone, vindesine, cyclophosphamide and 5-fluorouracil every 4 weeks. Tumour size was reassessed after three cycles of chemotherapy. Tumour response was evaluated according to World Health Organization criteria. Complete or partial response to chemotherapy was achieved in 26 patients (47%). Level of n-3 polyunsaturated fatty acids in adipose tissue was higher in the group of patients with complete or partial response to chemotherapy than in patients with no response or with tumour progression (P < 0.004). Among n-3 polyunsaturated, only docosahexaenoic acid (22:6n-3) was significantly associated with tumour response (P < 0.005). In a logistic regression analysis taking into account age, body mass index and tumour size, 22:6 n-3 level proved to be an independent predictor for chemosensitivity (P = 0.03). These results suggest that, in breast cancer, 22:6 n-3 may increase the response of the tumour to the cytotoxic agents used. © 1999 Cancer Research Campaig