The Curious Case of a Missing Gallbladder: An Unusual Presentation of a Cholecystoduodenal Fistula.

Large gallstones could erode through gallbladder wall to nearby structures, causing fistulas, gastric outlet obstruction and gallstone ileus. They typically occur in elderly patients with comorbidities carrying therapeutic challenges. We present a case of a middle-aged woman who was thought to have symptomatic cholelithiasis. Extensive adhesions precluded safe cholecystectomy. While hepatobiliary iminodiacetic acid scan and magnetic resonance imaging with cholangiopancreatography (MRI-MRCP) failed to visualize the gallbladder, computed tomography (CT) was consistent with cholecystoduodenal fistula. A very large gallstone was seen endoscopically in the duodenum, which was broken down into pieces using a large stiff snare.

Intraosseous gout mimicking giant cell tumor of the patella.

Intraosseous gout involving the patella is an unusual presentation of the common inflammatory crystal deposition disease. In most reported cases of gout in the patella, there is prominent involvement of the adjacent patellar or quadriceps tendons of the extensor mechanism. A report from Japan describes another pattern of deposition, with a lesion arising in the synchondrosis of a bipartite patella. We present a case of a patient with no known history of gout experiencing vague anterior knee pain and subtle but rapidly progressive findings of a patellar lucent lesion on radiographs. No other cause for the patient's pain was identified on imaging. No prominent involvement of surrounding tendinous structures on MRI, unipartite patellar morphology, normal serum uric acid levels, rapid growth, and nonspecific appearance of the lesion led to a working diagnosis of patellar giant cell tumor. Biopsy of the lesion was performed to guide further management, which yielded the unexpected result of crystalline deposits consistent with gout.

Chemoselective hydroamination of vinyl arenes catalyzed by an NHC-amidate-alkoxide Pd(II) complex and p-TsOH.

The hydroamination of various substituted vinyl arenes with benzenesulfonamide was explored using an NHC-amidate-alkoxide palladium catalyst in conjunction with p-TsOH. Utilizing halide-substituted and electron-rich vinyl arenes, this methodology selectively furnished the cross-coupled hydroamination products in moderate to excellent yields in a Markovnikov fashion while greatly reducing undesired acid-catalyzed homocoupling of the vinyl arenes. Electron-rich vinyl arenes typically required milder conditions than electron-poor ones. While most effective for para-substituted substrates, the catalyst system also furnished the desired products from ortho- and meta-substituted vinyl arenes with high chemoselectivities.

Crowding during restricted and free viewing.

Crowding impairs the perception of form in peripheral vision. It is likely to be a key limiting factor of form vision in patients without central vision. Crowding has been extensively studied in normally sighted individuals, typically with a stimulus duration of a few hundred milliseconds to avoid eye movements. These restricted testing conditions do not reflect the natural behavior of a patient with central field loss. Could unlimited stimulus duration and unrestricted eye movements change the properties of crowding in any fundamental way? We studied letter identification in the peripheral vision of normally sighted observers in three conditions: (i) a fixation condition with a brief stimulus presentation of 250 ms, (ii) another fixation condition but with an unlimited viewing time, and (iii) an unrestricted eye movement condition with an artificial central scotoma and an unlimited viewing time. In all conditions, contrast thresholds were measured as a function of target-to-flanker spacing, from which we estimated the spatial extent of crowding in terms of critical spacing. We found that presentation duration beyond 250 ms had little effect on critical spacing with stable gaze. With unrestricted eye movements and a simulated central scotoma, we found a large variability in critical spacing across observers, but more importantly, the variability in critical spacing was well correlated with the variability in target eccentricity. Our results assure that the large body of findings on crowding made with briefly presented stimuli remains relevant to conditions where viewing time is unconstrained. Our results further suggest that impaired oculomotor control associated with central vision loss can confound peripheral form vision beyond the limits imposed by crowding.