FROSTED BRANCH ANGIITIS IN METHIMAZOLE-INDUCED ANTINEUTROPHIL CYTOPLASMIC ANTIBODY-POSITIVE VASCULITIS

PURPOSE

To describe an unusual case of frosted branch angiitis that developed in a patient with acute onset systemic vasculitis possibly triggered by the antithyroid medication methimazole.

METHODS

We conducted a thorough review of the medical records of a 16-year-old female patient who presented with frosted branch angiitis. During the initial hospital admission, the patient underwent an extensive systemic workup to determine the etiology of her disease and ophthalmologic testing including fundus photographs and fluorescein angiography.

RESULTS

Our patient presented with a unilateral acute onset loss of vision, whose fundus examination revealed the pathognomonic features of frosted branch angiitis. Extensive systemic workup revealed an antineutrophilic cytoplasmic antibody-positive vasculitis, possibly triggered by methimazole.

CONCLUSION

This case is the first reported frosted branch angiitis associated with a drug-induced antineutrophilic cytoplasmic antibody-positive vasculitis triggered by methimazole.

Adenocarcinoma of the esophagus with signet ring cell features portends a poor prognosis

BACKGROUND

Adenocarcinoma with signet ring cell (SRC) features has been reported to be a poor prognostic marker in gastric and colorectal carcinomas. Although uncommon in the esophagus, SRC histology, interestingly, has been correlated with improved survival. Our impression has been that the incidence of esophageal adenocarcinomas with SRC features is increasing and is associated with worse outcomes. We hypothesize that patients with SRC histology present with more advanced disease, respond less well to induction therapy, and have decreased survival after resection compared with patients with non-SRC adenocarcinoma.

METHODS

The medical records of 151 consecutive patients who underwent resection for adenocarcinoma of the esophagus or gastroesophageal junction in a prospectively maintained database from 1998 to 2011 were reviewed. Outcomes of 23 patients (15%) with SRC histology (21 men, 2 women; average age, 66 years) were compared with 128 patients (85%) with non-SRC adenocarcinoma (116 men, 12 women; average age, 63 years). Overall survival, stage-specific survival, and response to induction therapy were evaluated. Cox regression multivariate analysis was used to identify independent predictors of 3-year survival.

RESULTS

SRC and non-SRC patients were evenly matched for clinical and tumor characteristics. Downstaging achieved with induction therapy was 13.3% (2 of 15) in SRC histology patients vs 67.1% (53 of 79) in non-SRC patients (p ≤ 0.001). Patients with SRC histology who did not respond well to induction treatment demonstrated strong trends toward a worse 3-year survival than patients with non-SRC adenocarcinoma (p = 0.084). The overall 3-year survival was 65.6% in patients without SRC histology vs 34.8% in those with SRC (p = 0.006). Patients with pathologic stage II or III and SRC histology had a 3-year survival of 27.3% compared with 57.4% in patients with non-SRC adenocarcinoma (p = 0.01). Multivariate analysis showed SRC histology trended toward significance as an independent risk factor for poor survival (p = 0.060).

CONCLUSIONS

Patients with adenocarcinoma of the esophagus or gastroesophageal junction and SRC histology respond less well to induction therapy and have decreased overall survival compared with patients with non-SRC histology.

A simplified procedure for the purification of large quantities of fetal bovine serum acetylcholinesterase

A simple procedure has been developed for the large scale purification of fetal bovine serum acetylcholinesterase (AChE) (EC 3.1.1.7). The procedure involves two steps: batch adsorption of the AChE from 250 L of serum onto a procainamide affinity Sepharose 4B gel; and analytical procainamide affinity chromatography of the step-1 product. Over 100 mg of AChE was purified in 10 days to apparent homogeneity with this procedure.

Aprophen: a substrate and inhibitor of butyrylcholinesterase and carboxylesterases

Aprophen, alpha-methyl-alpha-phenylbenzeneacetic acid-2-(diethylamino) ethyl ester, is a potent reversible inhibitor and a poor substrate of human serum butyrylcholinesterase (BuChE). Complex mixed competitive noncompetitive inhibition kinetics were observed; an apparent competitive inhibition constant was estimated to be 3.7 X 10(-7) M. BuChE hydrolysis of aprophen to diphenylpropionic acid and diethylaminoethanol did not appear to follow Michaelis-Menten kinetics. The BuChE turnover number for aprophen was 2.0 X 10(-3) sec-1. Rabbit liver oligomeric and monomeric carboxylesterases (CE) also hydrolyzed aprophen with a similar turnover number that varied from 1.4 X 10(-3) sec-1 to 4.3 X 10(-4) sec-1 respectively. Comparison of the catalytic rate of aprophen hydrolysis with butyrylthiocholine (BTC) and the neutral aromatic substrate, phenylthiobutyrate (phi TB), indicated that BuChE hydrolyzed BTC and phi TB 3.2 X 10(5) and 3.1 X 10(5) times more rapidly than aprophen respectively. Similarly, the CEs also hydrolyzed BTC and phi TB 17.6 and 1.9 X 10(5) times rapidly than aprophen. Acetylcholinesterases from bovine erythrocyte and electric eel were not inhibited by aprophen nor was aprophen hydrolyzed by these enzymes. The hydrolysis and inhibition reactions may best be described by a complex reaction scheme involving multiple binding sites for both the substrate and the inhibitor as well as positive cooperative ligand binding.

Acetylcholinesterase from fetal bovine serum. Purification and characterization of soluble G4 enzyme

Acetylcholinesterase (EC 3.1.1.7) from fetal bovine serum (FBS) was purified to electrophoretic homogeneity. The procedure involved procainamide affinity chromatography with native FBS, followed by chromatography on Sepharose 6B and DEAE-Sephadex. The acetylcholinesterase was purified approximately 44,000-fold, and 13 mg was obtained corresponding to an overall yield of about 45%. The purified acetylcholinesterase was stable at 4 degrees C for at least 8 weeks but was labile to freezing; however, in 50% glycerol the enzyme was stable at -20 degrees C for at least 12 weeks. FBS acetylcholinesterase exhibited typical substrate inhibition, had a Km of 120 microM, and a turnover number of 5300 s-1 with the substrate acetylthiocholine. The enzyme was highly sensitive to the specific acetylcholinesterase inhibitor 1,5-bis(4-allyldimethylammoniumphenyl)pentan-3-one. FBS acetylcholinesterase was characterized as a G4 form of acetylcholinesterase and was distinguished from bovine erythrocyte acetylcholinesterase on the basis of lectin gel binding, [3H] Triton X-100 binding, amino acid composition, number of catalytic subunits/molecule, and hydrodynamic properties. FBS acetylcholinesterase had a Stokes radius of 76 A as judged by gel filtration, and from this a molecular weight of 340,000 daltons was calculated. The enzyme had a subunit weight of approximately 83,000 daltons by sodium dodecyl sulfate-polyacrylamide gel electrophoresis; paraoxon titration indicated a relative active site mass of 75,000 daltons. The amino acid composition of FBS acetylcholinesterase was similar to the human erythrocyte acetylcholinesterase (Rosenberry, T. L., and Scoggin, D. M. (1984) J. Biol. Chem. 259, 5643-5652). A monoclonal antibody directed against human erythrocyte acetylcholinesterase, AE-2, (Fambrough, D. M., Engel, A. G., and Rosenberry, T. L. (1982) Proc. Natl. Acad. Sci. U.S.A. 79, 1078-1082) cross-reacted with FBS acetylcholinesterase.

Use of procainamide gels in the purification of human and horse serum cholinesterases

Two large-scale methods based primarily on the use of procainamide-Sepharose gels were developed for the purification of horse and human serum non-specific cholinesterases. With method I, the procainamide-Sepharose 4B gel was used in the first step to handle large volumes of serum. With method II, the procainamide-Sepharose 4B gel was used in the final step to obtain pure enzyme. Although both methods gave electrophoretically pure cholinesterase preparations in good yields, they were significantly more efficient at purifying the horse enzyme than the human enzyme. To study this problem, the relative binding of human and horse cholinesterases to procainamide-, methylacridinium (MAC)-, m-trimethylammoniophenyl (m-PTA)- and p-trimethylammoniophenyl (p-PTA)-Sepharose 4B gels were measured, by using two approaches. In one, binding was measured by a procedure involving equilibration of pure cholinesterase in a small volume of diluted gel slurry (4%, v/v). A partially purified preparation of Electrophorus acetylcholinesterase was included. Pure human cholinesterase bound consistently more tightly to each of the gels than did horse cholinesterase, and the acetylcholinesterase appeared to bind the gels 10-100 times more tightly than did the non-specific cholinesterases. The order of binding for the cholinesterases, beginning with the tightest, was: procainamide-Sepharose 4B, MAC-Sepharose 4B, p-PTA-Sepharose 4B and m-PTA-Sepharose 4B. For the acetylcholinesterase the order was: MAC-Sepharose 4B, procainamide-Sepharose 4B, p-PTA-Sepharose 4B and m-PTA-Sepharose 4B. The second approach involved passing native sera or partially purified sera fractions through 1 ml test columns of each of the four affinity gels to determine their retention capacity for the cholinesterases. With these impure samples, the MAC-Sepharose 4B gels proved superior to the procainamide-Sepharose 4B gels at retaining human cholinesterase, but the opposite was true for the horse cholinesterase.