Evaluation of the Pentax-AWS(®) and the Macintosh laryngoscope in difficult intubation: a manikin study.

BACKGROUND: The Pentax-AWS (AWS(®)), a new video laryngoscope, has been shown to be useful in cases of difficult intubation. We hypothesized that the AWS(®) would be more useful in the settings of a narrow upper airway than the Macintosh laryngoscope. We compared each device in simulated scenarios of representative difficulty of tracheal intubation using a manikin. The primary endpoint was the rate of successful intubation. METHODS: With each device, 23 anesthesiologists performed tracheal intubation in a SimMan(®) manikin in the following scenarios: (1) normal airway, (2) tongue edema, (3) cervical spine rigidity, (4) pharyngeal obstruction, (5) jaw trismus, (6) tongue edema with pharyngeal obstruction. The intubation time and success rate were measured. Each participant was asked to rate the difficulty of intubation (1=very easy; 5=very difficult). RESULTS: In the scenarios of tongue edema and tongue edema with pharyngeal obstruction, the AWS(®) yielded a higher success rate (100% vs. 34.8%; P<0.001, 65.2% vs. 21.7%; P=0.006), a shorter intubation time [14.6 (7.0) vs. 33.4 (13.0) s; P<0.001, 24.5 (12.0) vs. 37.6 (11.9); P=0.047; mean (standard deviation)], and a lower difficulty score [2 (1-4) vs. 5 (1-5); P<0.001, 4 (2-5) vs. 5 (3-5); P<0.001; median (range)], compared with the Macintosh laryngoscope. CONCLUSION: The AWS(®) has an advantage over the Macintosh laryngoscope in simulated tongue edema and tongue edema with pharyngeal obstruction. Further studies in a clinical setting are necessary to confirm these findings.

Roles of nitric oxide (NO) and NO synthases in healing of dextran sulfate sodium-induced rat colitis.

We examined the effects of various NO inhibitors on the healing of DSS-induced rat colitis. Experimental colitis was induced by feeding rats for 6 days with 2.5% DSS in drinking water. After DSS treatment, the animals were fed normally and killed various days up to 7 days later. L-NAME (a nonselective NOS inhibitor) or aminoguanidine (a selective iNOS inhibitor) was given p.o. twice daily for 6 days starting from the termination of DSS treatment. The area of lesions, colon length and MPO activity were measured on day 7 after DSS treatment. DSS treatment caused severe lesions in the colon, accompanied by an increase in MPO activity and a decrease in colon length. The lesions healed gradually after discontinuation of DSS treatment, with a histological restoration and subsidence of inflammation. The healing of DSS-induced colonic lesions was significantly impaired by daily administration of L-NAME or aminoguanidine, the effects being all but equivalent between these drugs, and the effect of L-NAME was significantly reverted by the co-administration of L-arginine. The expression of nNOS protein was observed in the colonic mucosa with or without DSS treatment, while those of iNOS and eNOS were markedly upregulated after DSS treatment. Likewise, the expression of VEGF was also up-regulated in the colon following DSS treatment, and this response was suppressed by both L-NAME and aminoguanidine. These results suggest that endogenous NO produced by mainly iNOS and partly eNOS contributes to the healing of DSS-induced colonic lesions, through the upregulation of VEGF expression and enhancement of angiogenesis.

Experimental and simulation analysis of community structure of nitrifying bacteria in a membrane-aerated biofilm.

Until now, only few attempts have been made to assess biofilm models simulating microenvironments in a biofilm. As a first step, we compare the microenvironment observed in a membrane aerated biofilm (MAB) to that derived from a two-dimensional computational model with individual ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) embedded in a continuum EPS matrix. Gradients of oxygen were determined by means of microelectrodes. The change in nitrifying bacterial populations with the biofilm depth was quantified using fluorescence in situ hybridization (FISH) in combination with a confocal laser scanning microscopy (CLSM). Microelectrode measurements revealed that oxic and anoxic or anaerobic regions exist within the MAB. The oxygen profile predicted by the model showed good agreement with that obtained by microelectrode measurements. The oxic part of the biofilm was dominated by NSO190 probe-hybridized AOB, which formed relatively large clusters of cells directly on the membrane surface, and by the NOB belonging to genus Nitrobacter sp. On the other hand, NOB belonging to genus Nitrospira sp. were abundant at the oxic-anoxic interface. The model prediction regarding AOB and Nitrobacter sp. distribution was consistent with the experimental counterpart. Measurements of AOB cluster size distribution showed that colonies are slightly larger adjacent to the membrane than at the inner part of the biofilm. The sizes predicted by the current model are larger than those obtained in the experiment, leading to the arguments that some factors not contained in the model would affect the cluster size.

Single-stage autotrophic nitrogen-removal process using a composite matrix immobilizing nitrifying and sulfur-denitrifying bacteria.

We developed a novel single-stage autotrophic nitrogen-removal process comprised of two composite immobilized biomass layers-one of nitrifying bacteria and one of sulfur-denitrifying bacteria and elemental sulfur-in a Fe-Ni fibrous slag matrix. Nitrification and consumption of dissolved oxygen occurred in the outer part and sulfur denitrification in the anoxic inner part of the composite matrix, thus realizing autotrophic nitrogen removal in a single reactor. The complete conversion of ammonia into N2 in a single reactor was demonstrated in both batch-mode incubation and continuous-feed operation. The spatial profiles of the ammonia-oxidizing bacteria and denitrifying bacteria were evaluated by real-time PCR, targeting their functional genes, and stratification of these two types was observed in the matrix after several months of incubation. This process does not require any specific reactor type or conditions and thus has the potential to be applied to many different wastewater treatment processes due to its simplicity in both operation and construction.

Quantitative analysis of amoA mRNA expression as a new biomarker of ammonia oxidation activities in a complex microbial community.

AIMS: To quantitatively analyse the changes to amoA mRNA (ammonia mono-oxygenase encoding mRNA) profiles in response to a change in ammonia oxidation activity in a complex microbial community. METHODS AND RESULTS: The amoA mRNA levels in both a batch-mode incubation and a continuously fed nitrification reactor were determined by real-time reverse transcription-PCR analysis. The amoA mRNA level changed rapidly in response to the change in environmental conditions which affect ammonia oxidation activity. CONCLUSION: An increase in amoA mRNA level can be detected within 1-2 h in response to an initiation of cell activity whereas a decrease in amoA mRNA level is detected within 24 h in response to a cessation of activity. SIGNIFICANCE AND IMPACT OF THE STUDY: amoA mRNA, which shows sensitive response to ammonia oxidation activity, can be used as a biomarker of ammonia oxidation activity in wastewater treatment processes where many bacterial species exist.

Transition of bacterial spatial organization in a biofilm monitored by FISH and subsequent image analysis.

The dynamic transition of bacterial community structure in a biofilm was monitored by the fluorescence in situ hybridization (FISH) technique and subsequent image analysis. Heterotrophic bacteria that had occupied the outer layer were gradually decreased whereas ammonia-oxidizing bacteria (AOB) gradually increased their growth activity and extended their existence area to the outer layer of the biofilm through the gradual reduction of the C/N ratio. The spatial organization of AOB in the biofilm dynamically changed responding to the environmental conditions such as pH fluctuation and lack of dissolved oxygen (DO) and had great influence on the nitrification activity. The accumulation of nitrite was observed at lower DO concentration, which might be due to the property that nitrite-oxidizing bacteria (NOB) possess of higher Km values for oxygen than AOB.

Real-time monitoring of ammonia-oxidizing activity in a nitrifying biofilm by amoA mRNA analysis.

Ammonia monooxygenase encoding mRNA (amoA mRNA) transcription in the wastewater treatment process was investigated using reverse transcription PCR (RT-PCR) as the model indicating specific function and activity in nitrifying processes. The dynamic response of amoA mRNA transcription and ammonia-oxidizing activity to the change of environmental conditions such as pH and concentration of ammonia was examined to determine the inductive factor and the inhibitor for amoA mRNA expression. Furthermore, we semiquantitatively investigated the response of amoA mRNA transcription to the pH fluctuation in a continuous fed nitrifying reactor. As a result, amoA mRNA oriented analysis enabled real-time assay of ammonia-oxidizing activity within 2 h as a response time. In contrast, rRNA and amoA encoding DNA were constantly detected at almost the same amount throughout the experiment. mRNA transcription was regulated by the many environmental conditions: ammonia seems to be one of the strong inducers for transcription of amoA mRNA, whereas low pH seems to be a strong inhibitor. These factors simultaneously affected the mRNA transcription and enzymatic activity leading to the complex phenomena of ammonia-oxidizing activity and amoA mRNA transcription in the continuous feeding reactors.

Flavin reductase coupling with two monooxygenases involved in dibenzothiophene desulfurization: purification and characterization from a non-desulfurizing bacterium, Paenibacillus polymyxa A-1.

The dibenzothiophene (DBT) desulfurizing bacterium metabolizes DBT to form 2-hydroxybiphenyl without breaking the carbon skeleton. Of the DBT desulfurization enzymes, DszC and DszA catalyze monooxygenation reactions, both requiring flavin reductase. We searched for non-DBT-desulfurizing microorganisms producing a flavin reductase that couples more efficiently with DszC than that produced by the DBT desulfurizing bacterium Rhodococcus erythropolis D-1, and found Paenibacillus polymyxa A-1 to be a promising strain. The enzyme was purified to complete homogeneity. K(m) values for FMN and NADH were 2.1 microM and 0.57 mM, respectively. Flavin compounds were good substrates, some nitroaromatic compounds were also active, and regarding the electron donor, the activity for NADPH was about 1.5 times that for NADH. In the coupling assay with DszC, only FMN or riboflavin acted as the electron acceptor. The coupling reactions of P. polymyxa A-1 flavin reductase with DszC and DszA proceeded more efficiently (3.5- and 5-fold, respectively) than those of R. erythropolis D-1 flavin reductase when identical enzyme activities of each flavin reductase were added to the reaction mixture. The result of the coupling reaction suggested that, in the microbial DBT desulfurization, flavin reductase from the non-DBT-desulfurizing bacterium was superior to that from the DBT-desulfurizing bacterium.

Isolation of Pseudomonas aeruginosa from Ushubetsu River water in Hokkaido, Japan.

To provide information on the ecology of Pseudomonas aeruginosa in nature, bacteriological surveillance was performed in the defined area in Hokkaido, Japan. P. aeruginosa was isolated from water samples of Ushubetsu River in the down stream from the urban area of Asahikawa. P. aeruginosa was isolated from fecal samples of pigs but not from samples of soil of a tomato field, sand of sandboxes in vest-pocket parks, fresh vegetables, or feces of wild deer. The present results indicate that P. aeruginosa strains isolated from the river water is originated from the environment of human activity and not from wild life or domestic animals.

Identification of the gene encoding a NAD(P)H-flavin oxidoreductase coupling with dibenzothiophene (DBT)-desulfurizing enzymes from the DBT-nondesulfurizing bacterium Paenibacillus polymyxa A-1.

The gene encoding NAD(P)H-flavin oxidoreductase (flavin reductase), which couples efficiently with dibenzothiophene (DBT)-desulfurizing monooxygenases of Rhodococci, was cloned from a DBT-non-desulfurizing bacterium Paenibacillus polymyxa A-1 in Escherichia coli, and designated as flv. Cell-free extracts from the recombinant exhibited a flavin reductase activity about forty times higher than that of the E. coli carrying the vector DNA only. Nucleotide sequence analysis reveals that the gene product consists of 208 amino acids and showed about 27%, 32% and 21% identity in amino acid sequence with FRase I, the major flavin reductase of Vibrio fischeri, the NADH dehydrogenase of Thermus thermophilus and several members of the nitroreductase family, respectively. The coexpression of flv with two kinds of desulfurizing genes, dszABC and tdsABC, in E. coli enhanced the rate of DBT degradation by about 10 and 5 times as high as in the case without flv, respectively.

Microbial ecology of nitrifying bacteria in wastewater treatment process examined by fluorescence in situ hybridization.

The microbial ecology of nitrifying bacteria in various types of wastewater treatment processes and the dynamic response of the microbial ecology in biofilms were investigated using fluorescence in situ hybridization (FISH) with 16S rRNA-targeted oligonucleotide probes. Nitrifying bacteria were found to exhibit various organizational forms under different conditions of substrate composition and concentration. Ammonia-oxidizing bacteria were dominant in ammonia-rich inorganic wastewater, while heterotrophic bacteria and ammonia-oxidizing bacteria were localized at different positions in the biofilm in organic wastewater. The dynamics of the microbial ecology in the biofilm with regard to the spatial distribution of ammonia-oxidizing bacteria and heterotrophic bacteria caused by a gradual change in substrate composition was successfully monitored by FISH analysis.

Ligation errors in DNA computing.

DNA computing is a novel method of computing proposed by Adleman (1994), in which the data is encoded in the sequences of oligonucleotides. Massively parallel reactions between oligonucleotides are expected to make it possible to solve huge problems. In this study, reliability of the ligation process employed in the DNA computing is tested by estimating the error rate at which wrong oligonucleotides are ligated. Ligation of wrong oligonucleotides would result in a wrong answer in the DNA computing. The dependence of the error rate on the number of mismatches between oligonucleotides and on the combination of bases is investigated.

Epidemiological study on periodontal diseases and some other dental disorders in dogs.

The prevalence of dental disorders in dogs was studied by applying index systems for human with some modifications. A total of 251 mongrel dogs including 143 stray dogs kept in the Animal Protection Offices in Tokyo and Hokkaido and 108 pet dogs visiting veterinary clinicians in Chiba Prefecture and Hokkaido were used. Periodontitis was prevalent among these dogs regardless of their sources and its incidence was increased with age. The lesion was more severe and more frequent in the premolar and molar regions than in the maxillary and mandibular incisor regions. Missing of teeth was observed at a high and increasing incidence with age. The tooth most commonly lost was the first premolar, followed by the other premolars and molars, where severe periodontitis was frequently found. Calculus was seen on many teeth, and aging agravated its prevalence and severity. Dental caries was observed in stray dogs, but neither to a serious degree nor at a significant level. These findings emphasize the necessity of dental hygiene, proper dental care and continuous periodical survey for dogs.

Oral flora of mongrel and beagle dogs with periodontal disease.

The plaque flora was studied in adult mongrel and beagle dogs with periodontal disease. Gingival plaque from maxillary premolars was removed and cultured on various growth media. The flora in all dogs was composed of mostly anaerobic gram negative rods. Bacteroides asaccharolyticus was found in the highest proportion of plaque samples from mongrel dogs, and decomposed hydrogen peroxide suggesting catalase activity. Fusobacterium nucleatum was found in higher proportion in the plaque of beagle dogs as compared to B. asaccharolyticus. With the increasing numbers of obligative anaerobic gram negative organisms such as B. asaccharolyticus, the proportions of Streptococcus, Enterococcus and Staphylococcus decreased in the dogs with periodontal disease. The salivary flora was different from the plaque flora of the dogs with periodontal disease. It was constant regardless with the disease. The salivary flora of beagle dogs with the healthy gingiva was different from that of mongrel dogs. Enterococcus, Lactobacillus, Eubacterium and black-pigmented Bacteroides (BPB, mainly B. asaccharolyticus) were higher proportion in the flora of beagle dogs as compared to mongrel dogs, while Fusobacterium, Enterobacteriaceae, yeast and molds were lower in the flora. The results reveal that B. asaccharolyticus and F. nucleatum are common pathogens and uniquely contribute to the development of gingival inflammation in dog.

Chemical analysis of glycosaminoglycans inhibiting DNA synthesis.

Sulfated glycosaminoglycans having inhibitory activity in cellular and subcellular systems were found in some tumor tissues from humans. These glycosaminoglycans inhibited more efficiently DNA synthesis of virus transformed cells (SV40-WIRL-3 cells) than their parent normal cells (WIRL-3 cells). Sulfated glycosaminoglycans found in normal human and non-tumor tissues did not have as high an inhibitory activity on DNA synthesis by cells used in this investigation as those from some human tumor tissues. The former did not inhibit as effectively DNA synthesis by virus transformed cells, as DNA synthesis by their normal parent cells. The monosaccharide composition of these sulfated glycosaminoglycans showed N-acetyl glucosamine (Glu-NAc) as a main monosaccharide, and xylose (Xyl), glucose (Glu), galactose (Gal), hyaluronic acid (Hu-A) as minor monosaccharides. N-acetyl galactosamine was not detected.