Carboxymethylation of an active site glutamic acid residue of ribonuclease F1 iodoacetate.

Ribonuclease (RNase) F1 was inactivated by incubation with an excess amount of iodoacetate at pH 5.5, 37 degrees C according to pseudo first-order kinetics. It was protected to various degrees, from inactivation by nucleotides, among which guanosine 2'-phosphate was most effective. The pseudo first-order rate constant was proportional to the reagent concentration, indicating that the reaction in reality follows second-order kinetics. The second-order rate constant was determined to be 25 x 10(-4) M-1 s-1. The inactivation rate was maximal at pH 5.5-6.0. When iodo[2-14C]acetate was used as the reagent, the stoichiometry of incorporation was determined to be 1.1 mol carboxymethyl group per mol of RNase F1 and glutamic acid residue 58 was assigned as the site of modification.

[A case of "interval" form of acute carbon monoxide poisoning--brain MRI and therapeutic effect of hyperbaric oxygenation].

A 43-year-old female who had suffered from paranoid reaction attempted suicide with city gas. She was admitted to an emergency hospital in a comatose state, regained consciousness the next day and was discharged 12 days after. However, on the 21st day after the poisoning, behavioral anomalies and staggering appeared. She was readmitted into another emergency hospital with the diagnosis of an "interval" form of acute carbon monoxide poisoning. She was performed hyperbaric oxygen therapy 42 times until the 53rd day after the accident. Nevertheless, her symptoms did not improve and remained in a state like an apallic syndrome. With little promise of improvement, she was moved to our hospital, and hyperbaric oxygen therapy further continued for 40 times which resulted in a remarkable recovery. Repeat EEGs were performed. On the 32nd day, EEG showed an abnormality consisting of generalized delta waves. On the 56th day, the abnormal EEG improved slightly with more alpha activity. EEG was normalized 126 days after. The X-ray CT scan on the 32nd day revealed low densities in the bilateral globus pallidus and the deep white matters adjacent to the frontal horns of the lateral ventricle and in the semioval centers. On the 57th day, these low density areas were depicted more clearly by the X-ray CT scan, which became less marked on the 73rd day. MRI was performed 3 times.(ABSTRACT TRUNCATED AT 250 WORDS)

[Oro-pharyngeal burn during electrodissection of the adenoid and tonsil].

We present a case of oro-pharyngeal burn which occurred during electrodissection of the adenoid and tonsil in a 5-year-old boy. We intubated the patient with an uncuffed spiral tube of appropriate size and noticed a slight gas leak during positive-pressure ventilation. Anesthesia was maintained with a mixture of 60% nitrous oxide, 40% oxygen and 2.5% sevoflurane. During manipulations of the right tonsil, orange-colored flame blew out about 5 cm from the mouth. Fortunately, the patient underwent the operative procedures without any further troubles, recovered fully from the grade 1 burn in the oral mucosa, and was discharged 23 days after surgery. The surgeons speculated that sevoflurane had been ignited. Although it is well known that sevoflurane is nonflammable in the concentration of clinical use, several reports show that sevoflurane is flammable in concentration of 10% under pure oxygen or nitrous oxide. We concluded that this accident was caused by electrocautery-induced ignition of the gauze packed into the larynx under a high concentration of oxygen which leaked through an uncuffed endotracheal tube. We have to bear in mind that any flammable substance may ignite when using electrocautery in a small space such as the mouth under oxygen-rich environment.