Langerhans cell histiocytosis of the atlas in an adult

Langerhans cell histiocytosis (LCH), formerly known as histiocytosis X, is a rare disorder (approximately 1:1,500,000 inhabitants) characterized by clonal proliferation and excess accumulation of pathologic Langerhans cells causing local or systemic effects. The exact etiology of LCH is still unknown. LCH could affect patients of any age, although most present when they are children. The most frequent sites of the bony lesions are the skull, femur, mandible, pelvis and spine. A variety of treatment modalities has been reported, but there was no evidence suggesting that any one treatment was more advantageous than another. We present an adult with LCH of the atlas. A 26-year-old young man presented with a 2-month history of neck pain and stiffness. CT revealed osteolytic lesion in the left lateral mass of atlas with compression fracture. Histopathological diagnosis was Langerhans cell histiocytosis by percutaneous needle biopsy under CT guidance. The patient underwent conservative treatment, including Halo-vest immobilization and radiotherapy. At 7-year follow-up, the patient was asymptomatic except for mild motion restriction of the neck. CT revealed a significant reconstruction of the C1 lateral mass

The Ubiquitin-Proteasome Pathway Mediates Gelsolin Protein Downregulation in Pancreatic Cancer

A well-known observation with respect to cancer biology is that transformed cells display a disturbed cytoskeleton. The underlying mechanisms, however, remain only partly understood. In an effort to identify possible mechanisms, we compared the proteome of pancreatic cancer with matched normal pancreas and observed diminished protein levels of gelsolin—an actin filament severing and capping protein of crucial importance for maintaining cytoskeletal integrity—in pancreatic cancer. Additionally, pancreatic ductal adenocarcinomas displayed substantially decreased levels of gelsolin as judged by Western blot and immunohistochemical analyses of tissue micoarrays, when compared with cancerous and untransformed tissue from the same patients (P < 0.05). Importantly, no marked downregulation of gelsolin mRNA was observed (P > 0.05), suggesting that post-transcriptional mechanisms mediate low gelsolin protein levels. In apparent agreement, high activity ubiquitin-proteasome pathway in both patient samples and the BxPC-3 pancreatic cancer cell line was detected, and inhibition of the 26s proteasome system quickly restored gelsolin protein levels in the latter cell line. The status of ubiquitinated gelsolin is related to lymph node metastasis of pancreatic cancer. In conclusion, gelsolin levels are actively downregulated in pancreatic cancer and enhanced targeting of gelsolin to the ubiquitin-proteasome pathway is an important contributing factor for this effect

Lineshape Analysis of the Beat Signal Between Optical Carrier and Delayed Sidebands

This paper presents the lineshape analysis of the beat signal between the optical carrier and the shifted and delayed side-bands produced by sinusoidal amplitude modulation. It is shown that the beat signal has a typical lineshape with a very narrow delta-peak superposed on a quasi-Lorentzian profile. Theoretical explanation for the appearance of this peak has been given based on optical spectral structure constructed by a large number of optical wave trains. It is predicted that the delta-peak is originated from the beat between the wave trains in the carrier and those in the delayed sidebands when their average coherence length is longer than the delay line. Experiments carried out using different delay lines clearly show that the delta-peak is always located at the modulation frequency and decreases with the increasing delay line. Our analysis explicitly indicates that the linewidth is related to the observation time. It is also suggested that the disappearance of the delta-peak can be used as the criterion of coherence elimination

Microwave generation in an electro-absorption modulator integrated with a DFB laser subject to optical injection

This paper presents a new technique to generate microwave signal using an electro-absorption modulator (EAM) integrated with a distributed feedback (DFB) laser subject to optical injection. Experiments show that the frequency of the generated microwave can be tuned by changing the wavelength of the external laser or adjusting the bias voltage of the EAM. The frequency response of the EAM is studied and found to be unsmooth due to packaging parasitic effects and four-wave mixing effect occurring in the active layer of the DFB laser. It is also demonstrated that an EA modulator integrated in between two DFB lasers can be used instead of the EML under optical injection. This integrated chip can be used to realize a monolithically integrated tunable microwave source. (C) 2009 Optical Society of Americ