Characterization of xylanolytic enzymes in Clostridium cellulovorans: expression of xylanase activity dependent on growth substrates.

Xylanase activity of Clostridium cellulovorans, an anaerobic, mesophilic, cellulolytic bacterium, was characterized. Most of the activity was secreted into the growth medium when the bacterium was grown on xylan. Furthermore, when the extracellular material was separated into cellulosomal and noncellulosomal fractions, the activity was present in both fractions. Each of these fractions contained at least two major and three minor xylanase activities. In both fractions, the pattern of xylan hydrolysis products was almost identical based on thin-layer chromatography analysis. The major xylanase activities in both fractions were associated with proteins with molecular weights of about 57,000 and 47,000 according to zymogram analyses, and the minor xylanases had molecular weights ranging from 45,000 to 28,000. High alpha-arabinofuranosidase activity was detected exclusively in the noncellulosomal fraction. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed that cellulosomes derived from xylan-, cellobiose-, and cellulose-grown cultures had different subunit compositions. Also, when xylanase activity in the cellulosomes from the xylan-grown cultures was compared with that of cellobiose- and cellulose-grown cultures, the two major xylanases were dramatically increased in the presence of xylan. These results strongly indicated that C. cellulovorans is able to regulate the expression of xylanase activity and to vary the cellulosome composition depending on the growth substrate.

A comparison of two silicone-reinforced tracheal tubes with different bevels for use with the intubating laryngeal mask.

Seventy consecutive patients were randomly allocated for intubation through the intubating laryngeal mask airway using a straight reinforced silicone tracheal tube with either a conventional or a modified bevel. The conventional bevel was firm, wedge-shaped and with a leading edge at the side. The modified bevel was soft, hemispherical and with a leading edge in the midline. The intubating laryngeal mask position was adjusted until optimal ventilation was obtained and intubation was attempted using the randomised device. If tactile resistance was felt, a predetermined sequence of adjusting manoeuvres were utilised before a subsequent attempt. The first-attempt successful intubation rate with the conventional bevel was 23/37 (62%) and with the modified bevel was 28/33 (85%). The second-attempt successful intubation rate for the conventional bevel was 12/37 (32%) and for the modified bevel was 4/33 (12%). Intubation failed after three attempts for one patient in each group. Fewer overall intubation attempts were required with the modified bevel (p = 0.033). We conclude that intubation success rates through the intubating laryngeal mask with a straight silicone-reinforced tube are higher with a soft, hemispherical bevel with a leading edge in the midline compared with the firm, wedge-shaped bevel with a leading edge at the side.

Airway management for an uncooperative patient with recessive dystrophic epidermolysis bullosa.

We describe a case of an unco-operative patient with recessive dystrophic epidermolysis bullosa in whom difficult tracheal intubation was anticipated and fibreoptic bronchoscope guided tracheal intubation was successfully achieved after induction of general anaesthesia. Other problems in airway management associated with this disorder are discussed.

Cellulose and Xylan Utilisation in the Lower Termite Reticulitermes speratus.

The distribution of the enzymes of cellulose and xylan metabolism namely endo-beta-1,4-glucanase, beta-glucosidase, endo-beta-1,4-xylanase and beta-xylosidase activities, in Reticulitermes speratus (Kolbe) was measured both in the salivary glands and in the major gut sections and along the length of the gut in freshly collected termites. The majority of the endo-beta-1,4-glucanase activity (77.8%) was found in the salivary glands which also contained 23.9% of the beta-glucosidase activity. At least 70% of the remaining activity was located in the anterior section of the hindgut. A small amount of endo-beta-1,4-xylanase activity (2.4%), but no beta-xylosidase activity, was present in the salivary glands. The majority of these activities were in the anterior section of the hindgut. The RQ of freshly collected termites at 25 degrees C was 1.03+/-0.01. Maintaining termites for 16 days on wood, cellulose and xylan showed that the RQ values of termites fed on wood or xylan were not significantly different from those of freshly collected termites but significantly increased when maintained on cellulose. The RQ of starved termites after 11 days was 0.81+/-0.02. There were three effects on protozoan populations of feeding termites xylan for 20 days. One species, Dinenympha parva was not affected, while five others, Pyrsonympha grandis, Holomastigotes elongatum, Dinenympha rugosa, Dinenympha leidy and Dinenympha porteri survived for 20 days but slowly decreased in numbers. The numbers of P. grandis and D. leidy surviving for 20 days were significantly different from those in starved termites. The third group comprising the two large species, Teratonympha mirabilis and Trichonympha agilis and three small species, Pyrsonympha modesta, Dinenympha exilis and Dinenympha nobilis disappeared within 15 days as in starved termites. It is suggested that protozoa in the first two groups are xylanolytic. Protozoan populations on wood and cellulose diets were not markedly affected. Selective removal of the protozoa by u.v. irradiation led to the loss of xylanolytic activity and a life span comparable to starved termites. Copyright 1997 Elsevier Science Ltd. All rights reserved

Preparation and antitumor activities of mitomycin C beta-(1-->6)-branched (1-->3)-beta-D-glucan conjugate.

The conjugate of mitomycin C (MMC) with carboxymethylated schizophyllan (CMSPG) which was prepared from monochloroacetic acid and schizophyllan (SPG), a beta-(1-->6)-branched (1-->3)-beta-D-glucan from Schizophyllum commune Fries, was synthesized by using 1-ethyl-3-(3-dimethylaminopropyl)- carbodiimide. The degree of the substitution of carboxymethyl groups in CMSPG was estimated as approximately 0.87, and locations of carboxymethyl groups in CMSPG were predominantly determined at O-4, O-6, and O-4, 6 positions in glucose residues. The contents of MMC in the conjugate were estimated to be between 8 and 12% (w/w). The conjugate showed successive monoexponential liberation, with a half-life of 7.2 h. Although the in vitro cytotoxicity of the conjugate against L1210 leukemia cells was similar to that of MMC when the cells were exposed for 24 and 48 h, the 50% growth-inhibitory concentration of the conjugate for L1210 was two times higher than that of MMC with exposure for 12 h. The antitumor activity of the conjugate against subcutaneously implanted sarcoma 180 solid tumor in mice by intraperitoneal (i.p.) administration was similar to that of MMC at a dose of 1.5 mg eq MMC per kg per d for both 7 times of continuous administration and 4 times of intermittent administration. However, the reduction in the number of leukocytes in the peripheral blood, which was the side effect of MMC, was suppressed by the intermittent administration of the conjugate. The conjugate maintained the ability to induce the tumor regressing factor and the neutrophil chemotactic factor in the serum.