Expectant management for abdominal pregnancy.

This is the first English language report describing the expectant management for abdominal pregnancy. The patient was a 31-year-old multiparous woman who was transferred to our hospital on suspicion of ectopic pregnancy. Her serum human chorionic gonadotropin was positive, and a poorly-vascularized mass measuring about 4 cm was visualized in the Douglas pouch by transvaginal ultrasonography, as well as by pelvic magnetic resonance imaging. Because the bilateral adnexa were apparently intact, she was diagnosed with abdominal pregnancy, and expectant management was commenced. Unexpectedly, the mass remained in situ for nearly 3 years after her serum human chorionic gonadotropin tested negative. Laparoscopic removal of the mass was finally required because of persistent defecation pain. This case illustrates that some abdominal pregnancies can be managed expectantly, as is the case with tubal pregnancies. During the expectant management, however, it should be considered that the abdominal pregnancy mass may persist for a longer period and cause moderate symptoms necessitating surgical removal.

Microbial diversity of mesophilic methanogenic consortium that can degrade long-chain fatty acids in chemostat cultivation.

We established a chemostat cultivation method for a mesophilic methanogenic consortium that could degrade long-chain fatty acids (LCFA) using a completely stirred tank reactor (CSTR) fed with synthetic wastewater containing oleic and palmitic acids as the carbon and energy sources. The critical dilution rate of the chemostat, in which most of the introduced LCFA were decomposed and mineralized, was 0.4 d(-1). The microbial community under steady-state condition at this dilution rate was analyzed by 16S rRNA gene sequencing. We detected the following major groups of methanogens within the archaeal community: the aceticlastic genera Methanosaeta and Methanosarcina and the hydrogenotrophic genus Methanospirillum. We also detected organisms that were closely related to fatty-acid oxidizing bacteria affiliated with the family Syntrophomonadaceae. However, bacteria belonging to the phyla Bacteroidetes and Spirochaetes, which are phylogenetically distant from known fatty-acid oxidizing bacteria, apparently predominated in the population, indicating that they play important roles in LCFA degradation within the chemostat.

Effect of dilution rate on metabolic pathway shift between aceticlastic and nonaceticlastic methanogenesis in chemostat cultivation.

Acetate conversion pathways of methanogenic consortia in acetate-fed chemostats at dilution rates of 0.025 and 0.6 day(-1) were investigated by using (13)C-labeled acetates, followed by gas chromatography-mass spectrometry (GC-MS) analysis of the CH(4) and CO(2) produced. Nonaceticlastic syntrophic oxidation by acetate-oxidizing syntrophs and hydrogenotrophic methanogens was suggested to occupy a primary pathway (approximately 62 to 90%) in total methanogenesis at the low dilution rate. In contrast, aceticlastic cleavage of acetate by aceticlastic methanogens was suggested to occupy a primary pathway (approximately 95 to 99%) in total methanogenesis at the high dilution rate. Phylogenetic analyses of transcripts of the methyl coenzyme M reductase gene (mcrA) confirmed that a significant number of transcripts of the genera Methanoculleus (hydrogenotrophic methanogens) and Methanosarcina (aceticlastic methanogens) were present in the chemostats at the low and high dilution rates, respectively. The mcrA transcripts of the genus Methanosaeta (aceticlastic methanogens), which dominated the population in a previous study (T. Shigematsu, Y. Tang, H. Kawaguchi, K. Ninomiya, J. Kijima, T. Kobayashi, S. Morimura, and K. Kida, J. Biosci. Bioeng. 96:547-558, 2003), were poorly detected at both dilution rates due to the limited coverage of the primers used. These results demonstrated that the dilution rate could cause a shift in the primary pathway of acetate conversion to methane in acetate-fed chemostats.

Effect of dilution rate on structure of a mesophilic acetate-degrading methanogenic community during continuous cultivation.

The community structures of two mesophilic acetate-degrading methanogenic consortia enriched at dilution rates of 0.025 and 0.6 d(-1) were analyzed by fluorescence in situ hybridization (FISH) and phylogenetic analyses based on 16S rDNA clonal sequences and quantitative real-time polymerase chain reaction (PCR). FISH experiments with archaeal and bacterial domain-specific probes showed that archaeal cells were predominant and only a small number of bacterial cells were detected at both dilution rates. In the domain Archaea, the number of cells closely related to Methanosarcina barkeri was shown to be greater at the high dilution rate using FISH with species-specific probes. Taxonomic analyses based on rDNA clonal sequences obtained at the low and high dilution rates showed that 43% of 100 clones and 72% of 92 clones, respectively, were affiliated with the domain Archaea and the remainders at each dilution rate were affiliated with the domain Bacteria. Within the domain Archaea, all rDNA clones at both dilution rates were affiliated with the genera Methanosaeta or Methanosarcina of the aceticlastic methanogens. Within the domain Bacteria, the rDNA clones obtained at the low dilution rate were affiliated with four phyla, Firmicutes (36%), Bacteroidetes (9%), Chloroflexi (6%) and candidate division OP12 (5%). The rDNA clones obtained at the high dilution rate were affiliated with four phyla, Firmicutes (16%), Bacteroidetes (8%), Proteobacteria (1%) and candidate division OP12 (3%). Real-time quantitative PCR experiments showed that the number of rDNA sequences affiliated with the genus Methanosarcina was greater at the high dilution rate. In addition, a significant number of rDNA sequences affiliated with the genus Methanoculleus were detected only at the low dilution rate. Detection of a hydrogenotrophic methanogen at the low dilution rate suggests that the syntrophic acetate oxidation by hydrogenotrophic methanogens and acetate-oxidizing bacteria could occur at the low dilution rate.