Solid-phase peptide synthesis at elevated temperatures: a search for an optimized synthesis condition of unsulfated cholecystokinin-12

A systematic investigation of solid-phase peptide synthesis at elevated temperatures using the well-known aggregating peptide acyl carrier protein (65–74) and the unsulfated cholecystokinin-8 as models is presented. The main goal of the investigation was the determination of an optimized experimental condition for the synthesis of unsulfated cholecystokinin-12. Of the elevated temperatures used, 60°C was the most appropriate. The efficiency of N, N'-diisopropylcarbodiimide/l-hydroxybenzotriazole (DIC/HOBt) in 25% dimethyl sulfoxide (DMSO)/toluene at this temperature was similar to that of 2-(1-H-benzotriazole-1-yl)-1, 1, 3, 3-tetramethyluronium tetrafluoroborate (TBTU). Interestingly, this coupling reagent was more efficient than TBTU, benzotriazol-1-yl oxy-tris(dimethylamino)phosphonium and O-(7-azabenzotriazol-1-yl)-1, 1, 3, 3-tetramethyluronium hexafluorophosphate in N-methylpyrrolidone. 25%DMSO/toluene proved to be suitable for the swelling of the resins phenylacetamidomethyl, methylbenzhydrylamine, hydroxymethylphenoxy, 4-(benzyloxy)-2′, 4′-dimethoxybenzhydrylamine, 4-(2′, 4′-dimethoxyphenyl-Fmoc-aminomethyl)phenoxy and (4-succinylamido-2′, 2′, 4′-trimethoxy)benzhydrylamine. Those polymeric supports were fully compatible with the approach. Under the optimized synthesis condition found in these studies (temperature of 60°C, DIC/HOBt as coupling reagent and 25%DMSO/toluene as solvent), no difficulties related to the aggregation phenomenon were encountered. These data confirm the usefulness of solid-phase peptide synthesis at elevated temperatures and extend its applicability.     

Airflow measurement inaccuracies in aerosol imaging

Aerosol production using inclined compressed air tanks may be subject to error caused by airflow meter variability and by the degree of inclination of the air-flow meter. Since most of these tanks are used in an inclined position, it is important for clinicians to be aware of these errors.     

Transoral approach to the cervical spine: report of four cases

The transoral approach to the upper cervical spine is an established but little used route, offering excellent access with good wound healing, to lesions of the bodies of the atlas, axis and upper part of the third cervical vertebra. The authors report four cases which demonstrate the value of the procedure.     

Transcatheter embolization of coronary artery fistula with controlled release coils

ABSTRACT The treatment for large congenital coronary cameral fistulas has been surgical but with advances in interventional catheterization techniques transcatheter embolization of these fistulas with coils or detachable balloons is now possible. This report describes occlusion of a congenital coronary arteriovenous fistula in a 6-year-old girl.     

Cholelithiasis: evaluation with CT

Computed tomography (CT) is often the first imaging modality used in the diagnosis of patients with suspected abdominal disease. While it is known that early generation CT scanners often detect gallstones, the detection rate of newer equipment is not widely known. Abdominal CT scans of 226 patients who had undergone ultrasonographic (US) studies of the gallbladder were reviewed in a blinded study to determine the accuracy of state-of-the-art CT scanning equipment in the detection of cholelithiasis. Of 110 patients with US or surgical evidence of cholelithiasis, gallstones were demonstrated on CT images of 87 (79.1% sensitivity). Overall accuracy was 89.8%, while specificity was 100%. On CT images stones could appear densely (48.3%) or slightly (11.5%) calcified, as an area with a rim of increased density (21.8%), as an area of soft-tissue density (14.9%), or as an area of low density (3.4%). Stone size, stone density, section incrementation, and the pericholecystic anatomy affected the detection rate. Understanding the spectrum of findings and the other factors involved can optimize success of diagnosis of cholelithiasis on the basis of CT examinations.