Recombinant expression and purification of phenylalanyl-tRNA synthetase from wheat: a long-lasting poly(U)-dependent poly(Phe) synthesis system.

Synthetic genes for the two subunits of phenylalanyl-tRNA synthetase (PheRS) from wheat were expressed in Escherichia coli. When each gene was induced individually, the α subunit with a cleavable 6 × His tag at the amino terminus was largely soluble, while the ß subunit was almost completely insoluble. When the two subunits were co-expressed, a soluble fraction containing the two subunits were obtained. This was purified by a standard method in which the tag was cleaved off with a specific protease after affinity purification. As the sample contained slightly more PheRSα than PheRSß, we further resolved the sample by gel filtration to obtain the fraction that showed the size of the conventional α2ß2 tetrameric complex and contains an almost equal amount of the two subunits. The final yield was 0.6 mg per 1 liter of the culture medium, and the specific activity was 28 nmol min-1 mg-1, which was higher than that of a fraction purified from wheat germ. This recombinant PheRS was used, along with purified samples of the elongation factors and the ribosomes from wheat germ, for a poly(U)-dependent poly(Phe) synthesis reaction. The reaction was dependent on the added components and lasted for more than several hours.

Can the lower rate of CT- or MRI-related adverse drug reactions to contrast media due to stricter limitations on patients undergoing contrast-enhanced CT or MRI?

OBJECTIVE: The aim of this study was to examine whether a decreased occurrence rate of adverse drug reactions (ADRs) to contrast media in contrast-enhanced CT and MRI was attributable to appropriate criteria for patients with some diseases. A secondary aim was to elucidate safety profiles for contrast media and factors influencing the occurrence of ADRs. METHODS: Clinical data of patients who underwent contrast-enhanced CT (5576 cases) or MRI (3357 cases) were retrospectively analyzed to evaluate rates of ADRs to contrast media, symptoms of ADRs, treatments for ADRs, and differences in medical history, blood test results, and other factors between patients with and without ADRs in a dental hospital. RESULTS: The rate of ADRs to contrast media was 0.54% for CT and 0.09% for MRI. The most frequent ADRs in contrast-enhanced CT or MRI were nausea and vomiting as physiologic reactions. Two serious reactions were seen for CT, but none for MRI. Significant differences between patients with and without ADRs were seen in liver function according to blood tests for CT, and in digestive disorders elicited from medical interviews for MRI. CONCLUSION: The lower occurrence rate of ADRs to contrast media in dental hospitals could be due to the adoption of appropriate criteria for patients with some diseases undergoing enhanced CT or MRI. Complete suppression of ADRs to contrast media for CT or MRI is unrealistic, so attention is warranted for patients with decreased liver function when performing enhanced CT, and for patients with digestive disorders when performing enhanced MRI.

Advocacy of diagnostic criteria for maxillary incisive canal cysts based on alteration of normal maxillary incisive canals according to aging in Japanese populations.

BACKGROUND: The purpose of the present study was to describe the CT imaging findings of normal incisive canals and incisive canal cysts and propose cut-off values to differentiate between them. METHODS: A total of 220 normal subjects and 40 patients with incisive canal cysts on multi-detector row computed tomography (MDCT) were retrospectively analyzed. The shapes, sizes, anatomic variations, Hounsfield scale values, and so on of maxillary incisive canals and the sizes and Hounsfield scale values of maxillary incisive canal cysts were analyzed. RESULTS: A significant difference in sizes of maxillary incisive canals in normal subjects was found between males and females. The sizes of maxillary incisive canals were significantly wider during aging, but shapes, anatomic variations, and Hounsfield scale values in the maxillary incisive canals were not significantly different with aging. A significant difference in sizes but not Hounsfield scale values was found between normal maxillary incisive canals and maxillary incisive canal cysts. Based on a cut-off of over 6 mm in the width of incisive canals, maxillary incisive canal cysts could not be appropriately diagnosed for subjects over 60 years of age. Over 60 years of age, maxillary incisive canal cysts could be appropriately diagnosed based on a cut-off of over 7.1 mm in width of incisive canals. When maxillary incisive canals of the hourglass types were seen on sagittal sections, significantly more patients had maxillary incisive canal cysts than other types. CONCLUSION: In coincidentally diagnosing asymptomatic incisive canal cysts on imaging, we should apply different cut-offs for the size of the maxillary incisive canal for patients over and under 60 years of age. Specifically, the cut-offs for the long axis of maxillary incisive canal cysts were 7.1 mm for patients over 60 years of age and 6.0 mm for those under 60 years of age. In addition, we should pay attention to wider canals with hourglass shapes as indicative of cystic change of maxillary incisive canals.