Two cases of chronic knee pain caused by unusual injuries to the popliteus tendon.

Injuries to the popliteus tendon are less frequent than injuries to the menisci or ligamentous structures of the knee. When they do occur, injuries to the popliteus tendon tend to be the result of trauma and associated with injuries to other components of the knee. The most commonly seen injuries include tears at the musculotendinous junction and avulsion tears at the lateral femoral condyle insertion site. This report presents two unusual injuries of the popliteus tendon in patients with chronic knee pain: an isolated split tear of the tendon and a subluxed tendon residing within the lateral joint space.

Gorham-Stout disease presenting with dyspnea and bone pain in a 9-year-old girl.

Gorham-Stout (GS) disease is a rare bone disorder of unknown etiology that is characterized by local proliferation of small vascular or lymphatic channels, resulting in progressive osteolysis and bone resorption. The diagnosis of GS disease is one of exclusion, with radiography and histopathology playing key roles. We describe a 9-year-old girl who presented to us with dyspnea and bone pain. She was found to have a cystic mass of the upper extremity, multiple cystic bone lesions, multiple fractures of different ages, and pleural effusions. We review the radiologic images that helped establish the diagnosis of GS disease.

Imaging of disorders affecting the bone and skin.

There are a variety of conditions that manifest not only in bone but also in skin. Bone and skin structures can share common embryologic origins, and genetic defects that occur early in cell differentiation may lead to disease in both organ systems. Alternatively, diseases of bone and skin may be caused by defects in genes that participate in directing or controlling both systems. Many diseases of bone and skin can manifest with atypical radiologic findings or mimic malignant bone lesions. Upon encountering such a disease process, a radiologist who is familiar with both aspects of the disorder and consequently looks for associated skin findings can greatly benefit the patient by making a definitive diagnosis. Similarly, a clinician who encounters suggestive skin lesions should be prompted to look for concomitant skeletal lesions. By synthesizing knowledge of bone and skin manifestations, radiologists and clinicians can help correctly diagnose a number of these disease processes, thereby helping patients avoid further, often nonspecific invasive workup and advancing patient care.

Radiographic findings of Proteus Syndrome.

The extremely rare Proteus Syndrome is a hamartomatous congenital syndrome with substantial variability between clinical patient presentations. The diagnostic criteria consist of a multitude of clinical findings including hemihypertrophy, macrodactyly, epidermal nevi, subcutaneous hamartomatous tumors, and bony abnormalities. These clinical findings correlate with striking radiographic findings.

Selection of hyperfunctional siRNAs with improved potency and specificity.

One critical step in RNA interference (RNAi) experiments is to design small interfering RNAs (siRNAs) that can greatly reduce the expression of the target transcripts, but not of other unintended targets. Although various statistical and computational approaches have been attempted, this remains a challenge facing RNAi researchers. Here, we present a new experimentally validated method for siRNA design. By analyzing public siRNA data and focusing on hyperfunctional siRNAs, we identified a set of sequence features as potency selection criteria to build an siRNA design algorithm with support vector machines. Additional bioinformatics filters were also included in the algorithm to increase RNAi specificity by reducing potential sequence cross-hybridization or microRNA-like effects. Independent validation experiments were performed, which indicated that the newly designed siRNAs have significantly improved performance, and worked effectively even at low concentrations. Furthermore, our cell-based studies demonstrated that the siRNA off-target effects were significantly reduced when the siRNAs were delivered into cells at the 3 nM concentration compared to 30 nM. Thus, the capability of our new design program to select highly potent siRNAs also renders increased RNAi specificity because these siRNAs can be used at a much lower concentration. The siRNA design web server is available at http://www5.appliedbiosystems.com/tools/siDesign/.