Acoustic destruction of a microcapsule having a hard plastic shell is discussed. In an ultrasonic drug delivery system, microcapsules having thin elastic shells release drugs that are contained therein when the shell is destroyed. In this paper, two subjects related to capsule destruction are discussed: the driving pulse duration for capsule destruction and the frequency dependence of capsule destruction. Optical observation of microcapsule destruction is performed with a high-speed video camera. In the case of capsule destruction by a pulse wave, the internal gas of the microcapsule cannot be ejected completely, and a portion of the internal gas remains inside the broken shell. It is found that capsule destruction by pulse waves depends on both the amplitude of the driving pressure and the pulse duration. The frequency dependence of microcapsule destruction also is investigated. In the case of capsule destruction by a low-amplitude acoustic wave, the destruction rate under the resonance condition is higher than under nonresonance conditions. By controlling the driving frequency, selective capsule destruction can be achieved.

Cu,Zn-superoxide dismutase (SOD) of bovine erythrocytes is a dimeric enzyme of identical subunits associated through unusually strong noncovalent interactions. It is known not to be dissociated into subunits even in 8 M urea for 72 h at 25 degrees C [Malinowski, D.P. & Fridovich, I. (1979) Biochemistry 18, 5055-5060]. Effects of urea, temperature, and SOD concentration on the inactivation and dissociation into subunits were examined. The activation energy of the inactivation of SOD (at 0.05 mg/ml) was 64 kcal/mol at pH 7.8, and was decreased to 40 kcal/mol in the presence of urea (2.0-7.3 M). The apparent first-order rate constant (kapp) of the inactivation by urea was dependent on the SOD concentration [SOD] during the urea treatment, and SOD showed a higher resistance to the inactivation with increase in the concentration. Dissociation of SOD was monitored by gel filtration HPLC. When SOD solutions of various concentrations were incubated in 6 M urea at 45 degrees C, two monomer species (M1 and M2) were observed in addition to dimer (D). The dimer maintained full activity, while the monomers did not show the activity. The peak areas of these species were changed depending on the SOD concentration during urea treatment; at over 15 mg/ml, almost all SOD was eluted as D, and with a decrease in the SOD concentration, the peak area of D decreased and concomitantly the monomers appeared. M2 could be the sole form in infinitely diluted SOD solution, and D was considered to be converted to M2 through M1. The SOD concentration giving 50% D ([SOD]1/2) was 1.0 mg/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Rituximab (RTX) is effective for treating cancer, but reports of RTX-associated enterocolitis are limited. We herein report the case of a 65-year-old man who developed RTX-induced ileocolitis. He was diagnosed with gastric mucosa-associated lymphoid tissue lymphoma (MALToma) and treated with RTX. He complained of bloody diarrhea after RTX. Mucosal inflammation on colonoscopy indicated RTX-induced ileocolitis. He was treated with corticosteroids, and his symptoms improved. We reviewed the RTX-associated gastrointestinal adverse events and classified the features into ulcerative colitis, Crohn's disease, microscopic colitis, and ileocolitis. To our knowledge, this is the first case of a Japanese patient who developed RTXinduced ileocolitis.

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