On the Influence of Intra - and Inter-Molecular Hydrogen Bonding on the Excited State Lifetime of Indigo Dyes

It is shown that intramolecular hydrogen bonding can give rise to very fast nonradiative desactivation of the S1 -state of indigo dyes. In those derivatives, which lack the possibility of internal hydrogen bonds, hydrogen bonding to suitable solvent molecules can provide the channel for fast radiationless transitions. As a consequence, drastic effects on the S1 -state lifetime are observed both as a function of solvent and/or temperature.

Perspectives of digestive pest control with proteinase inhibitors that mainly affect the trypsin-like activity of Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae)

The present study describes the main characteristics of the proteolytic activities of the velvetbean caterpillar, Anticarsia gemmatalis Hübner, and their sensitivity to proteinase inhibitors and activators. Midguts of last instar larvae reared on an artificial diet were homogenized in 0.15 M NaCl and centrifuged at 14,000 g for 10 min at 4 degrees C and the supernatants were used in enzymatic assays at 30 degrees C, pH 10.0. Basal total proteolytic activity (azocasein hydrolysis) was 1.14 +/- 0.15 absorbance variation min(-1) mg protein(-1), at 420 nm; basal trypsin-like activity (N-benzoyl-L-arginine-p-nitroanilide, BApNA, hydrolysis) was 0.217 +/- 0.02 mmol p-nitroaniline min(-1) mg protein(-1). The maximum proteolytic activities were observed at pH 10.5 using azocasein and at pH 10.0 using BApNA, this pH being identical to the midgut pH of 10.0. The maximum trypsin-like activity occurred at 50 degrees C, a temperature that reduces enzyme stability to 80 and 60% of the original, when pre-incubated for 5 and 30 min, respectively. Phenylmethylsulfonyl fluoride inhibited the proteolytic activities with an IC50 of 0.39 mM for azocasein hydrolysis and of 1.35 mM for BApNA hydrolysis. Benzamidine inhibited the hydrolysis with an IC50 of 0.69 and 0.076 mM for azocasein and BApNA, respectively. The absence of cysteine-proteinases is indicated by the fact that 2-mercaptoethanol and L-cysteine did not increase the rate of azocasein hydrolysis. These results demonstrate the presence of serine-proteinases and the predominance of trypsin-like activity in the midgut of Lepidoptera insects, now also detected in A. gemmatalis, and suggest this enzyme as a major target for pest control based on disruption of protein metabolism using proteinase inhibitors.

[An epidural spinal abscess with caudal symptoms as a complication of Crohn's disease]

Progressive symptoms of caudal compression (flaccid paraparesis, sensory disorders), accompanied by severe pain and fever, developed over a few days in a 26-year-old man with Crohn's disease for 11 years. Spinal computed tomography, performed under the diagnosis of herniated disc, revealed intraspinal soft tissue, as well as gas in the spinal canal (L2-S3) and the paravertebral muscles. This led to the diagnosis of acute epidural abscess and a laminectomy was performed (at L4-S2). Intraspinally there was thickened, bluish fatty tissue; thick pus exuded between dura and the sacral roots. Suction-irrigation of the spinal canal was undertaken via an epidural drain. Postoperative contrast infusion into the colon demonstrated a fistula directed towards the sacrum. The postoperative course was complicated by severe respiratory impairment of which the patient died.--Epidural abscess is a rare complication of Crohn's disease. Because of its poor prognosis early diagnosis with magnetic resonance imaging or computed tomography should be undertaken in every patient with Crohn's disease who has back pain, fever or, particularly, symptoms of spinal compression.