[Definition and diagnosis of acute-on-chronic liver failure: new knowledge and implication]

Acute-on-chronic liver failure (ACLF) is a common critical and severe syndrome in patients with chronic liver diseases in China and other countries in the Asia-Pacific region. In recent years, both the Eastern and Western experts have defined ACLF as a new type of liver disease manifesting as a high 28-day mortality rate (>30%) and extensive systematic inflammatory response. ACLF has become a hot topic in the field of liver diseases. This article reviews the research advances in the definition and etiological spectrum of ACLF and discusses the inspirations of such new knowledge for future research.

Diverse vaginal microbiomes in reproductive-age women with vulvovaginal candidiasis

Vulvovaginal candidiasis (VVC) is one of the most prevalent vaginal infectious diseases, and there are controversial reports regarding the diversity of the associated vaginal microbiota. We determined the vaginal microbial community in patients with VVC, bacterial vaginosis (BV), and mixed infection of VVC and BV using Illumina sequencing of 16S rRNA tags. Our results revealed for the first time the highly variable patterns of the vaginal microbiome from VVC patients. In general, the alpha-diversity results of species richness and evenness showed the following order: normal control < VVC only < mixed BV and VVC infection < BV only. The beta-diversity comparison of community structures also showed an intermediate composition of VVC between the control and BV samples. A detailed comparison showed that, although the control and BV communities had typical patterns, the vaginal microbiota of VVC is complex. The mixed BV and VVC infection group showed a unique pattern, with a relatively higher abundance of Lactobacillus than the BV group and higher abundance of Prevotella, Gardnerella, and Atopobium than the normal control. In contrast, the VVC-only group could not be described by any single profile, ranging from a community structure similar to the normal control (predominated with Lactobacillus) to BV-like community structures (abundant with Gardnerella and Atopobium). Treatment of VVC resulted in inconsistent changes of the vaginal microbiota, with four BV/VVC samples recovering to a higher Lactobacillus level, whereas many VVC-only patients did not. These results will be useful for future studies on the role of vaginal microbiota in VVC and related infectious diseases.

Comparison of microbial diversity determined with the same variable tag sequence extracted from two different PCR amplicons

BACKGROUND

Deep sequencing of the variable region of 16S rRNA genes has become the predominant tool for studying microbial ecology. As sequencing datasets have accumulated, meta-analysis of sequences obtained with different variable 16S rRNA gene targets and by different sequencing methods has become an intriguing prospect that remains to be evaluated experimentally.

RESULTS

We amplified a group of fecal samples using both V4F-V6R and V6F-V6R primer sets, excised the same V6 fragment from the two sets of Illumina sequencing data, and compared the resulting data in terms of the α-diversity, β-diversity, and community structure. Principal component analysis (PCA) comparing the microbial community structures of different datasets, including those with simulated sequencing errors, was very reliable. Procrustes analysis showed a high degree of concordance between the different datasets for both abundance-weighted and binary Jaccard distances (P < 0.05), and a meta-analysis of individual datasets resulted in similar conclusions. The Shannon's diversity index was consistent as well, with comparable values obtained for the different datasets and for the meta-analysis of different datasets. In contrast, richness estimators (OTU and Chao) varied significantly, and the meta-analysis of richness estimators was also biased. The community structures of the two datasets were obviously different and led to significant changes in the biomarkers identified by the LEfSe statistical tool.

CONCLUSIONS

Our results suggest that beta-diversity analysis and Shannon's diversity are relatively reliable for meta-analysis, while community structures and biomarkers are less consistent. These results should be useful for future meta-analyses of microbiomes from different data sources.

Comparison of direct boiling method with commercial kits for extracting fecal microbiome DNA by Illumina sequencing of 16S rRNA tags

Low cost and high throughput capacity are major advantages of using next generation sequencing (NGS) techniques to determine metagenomic 16S rRNA tag sequences. These methods have significantly changed our view of microorganisms in the fields of human health and environmental science. However, DNA extraction using commercial kits has shortcomings of high cost and time constraint. In the present study, we evaluated the determination of fecal microbiomes using a direct boiling method compared with 5 different commercial extraction methods, e.g., Qiagen and MO BIO kits. Principal coordinate analysis (PCoA) using UniFrac distances and clustering showed that direct boiling of a wide range of feces concentrations gave a similar pattern of bacterial communities as those obtained from most of the commercial kits, with the exception of the MO BIO method. Fecal concentration by boiling method affected the estimation of α-diversity indices, otherwise results were generally comparable between boiling and commercial methods. The operational taxonomic units (OTUs) determined through direct boiling showed highly consistent frequencies with those determined through most of the commercial methods. Even those for the MO BIO kit were also obtained by the direct boiling method with high confidence. The present study suggested that direct boiling could be used to determine the fecal microbiome and using this method would significantly reduce the cost and improve the efficiency of the sample preparation for studying gut microbiome diversity.

Illumina sequencing of 16S rRNA tag revealed spatial variations of bacterial communities in a mangrove wetland

The microbial community plays an essential role in the high productivity in mangrove wetlands. A proper understanding of the spatial variations of microbial communities will provide clues about the underline mechanisms that structure microbial groups and the isolation of bacterial strains of interest. In the present study, the diversity and composition of the bacterial community in sediments collected from four locations, namely mudflat, edge, bulk, and rhizosphere, within the Mai Po Ramsar Wetland in Hong Kong, SAR, China were compared using the barcoded Illumina paired-end sequencing technique. Rarefaction results showed that the bulk sediment inside the mature mangrove forest had the highest bacterial α-diversity, while the mudflat sediment without vegetation had the lowest. The comparison of β-diversity using principal component analysis and principal coordinate analysis with UniFrac metrics both showed that the spatial effects on bacterial communities were significant. All sediment samples could be clustered into two major groups, inner (bulk and rhizosphere sediments collected inside the mangrove forest) and outer mangrove sediments (the sediments collected at the mudflat and the edge of the mangrove forest). With the linear discriminate analysis scores larger than 3, four phyla, namely Actinobacteria, Acidobacteria, Nitrospirae, and Verrucomicrobia, were enriched in the nutrient-rich inner mangrove sediments, while abundances of Proteobacteria and Deferribacterias were higher in outer mangrove sediments. The rhizosphere effect of mangrove plants was also significant, which had a lower α-diversity, a higher amount of Nitrospirae, and a lower abundance of Proteobacteria than the bulk sediment nearby.

Turbulence under the microscope

Our objective was to observe a new form of turbulence caused bybiological effects - biological micro-turbulence and explore itsprocess and controlling factors. The methods used were proteusmirabilis CGCs micro-cultured to render the occurrence of the specific movement on micro-organic suspension and its controllingfactors were determined by comparison with the control trials.The results showed that turbulence under the microscope was generally in a mass but partially regular. It was also confirmedthat the turbulence under the microscope exhibited hollow effect,temperature-dependent switching on of occurrence and self-controlof suspension quantity. It is clarified that this new form ofturbulence is a spontaneous and self-control process, which providesan experimental model with controllable conditions for studies ofturbulence and a new way for researches on the mechanism andphysiological functions of the flow of body liquid.

[A new ecdysone hormone rhaponticum from Rhaponticum uniflorum (L.) DC]

OBJECTIVE

To study the chemical constituents of Rhaponticum uniflorum.

METHOD

Solvent extraction, separation by silica gel column chromatography and identification by physico-chemical properties and spectral data.

RESULT

A new ecdysone hormone, rhaponticum (1) was isolated from the root of R. uniflorum together with a known compound ecdysterone(2).

CONCLUSION

The two compounds were obtained from the plant for the first time.

[Etiological features and abnormal cerebrospinal fluid findings in 101 patients with suspected intracranial infections]

101 patients (44 males, 57 females) with suspected intracranial infections were admitted to PUMC Hospital from 1988 to 1993. Their age ranged from 16 to 65 years (mean 29). Based on etiological categories, viral meningitis or encephalitis was diagnosed in 37.6% of the patients, purulent meningitis in 20.8%, tuberculous meningitis in 19.8%, cryptococcal meningitis in 5.9%, cerebral cysticercosis in 5.9%, infections of unknown etiology in 5.0%, and noninfectious diseases in 4.0%. During hospitalization, the mortality rate for cryptococcal, tuberculous and purulent meningitis was 33.3%, 20.0% and 14.3% respectively. This study also showed that cerebrospinal fluid examination was helpful for etiological analysis or differential diagnosis of intracranial infections.

[Prevention and antibiotic treatment of Pseudomonas aeruginosa septicemia]

Thirty-six cases of pseudomonas aeruginosa septicemia were found in 5 years from 1986 to 1990. The main risk factors predisposing septicemia included severe underlying diseases and local primary infection or impaired anatomic barrier. The use of broad-spectrum antibiotics, cytotoxic or immunosuppressive therapy, and leukopenia were also important risk factors. The percentages of in vitro resistant strains to 8 antipseudomonal antibiotics varied from 18% to 47%. The overall effective rate was 42% in 26 patients receiving appropriate antibiotic therapy. The mortality attributable to pseudomonas aeruginosa septicemia was 61%. The prevention and antibiotic treatment of pseudomonas aeruginosa septicemia are discussed.

[Bacterial sepsis and nosocomial infection: a study of 70 patients]

74 episodes of bacterial sepsis in 70 patients were analysed from July 1988 to June 1989. The incidence of sepsis is 0.7% of the whole admitted patients. Compared to a similar previous study from April 1982 to March 1983, the incidence of sepsis decreased (P less than 0.01), and the incidence of nosocomial sepsis remained unchanged, whereas its mortality decreased (P less than 0.05). The host defenses are important in predisposing to sepsis and determining prognosis. Antibiotic sensitivity test revealed that some bacterial strains were resistant to new beta-lactam antibiotics.

[Clinical analysis of 130 patients with fever of unknown origin]

Hospital records of 130 patients with fever of unknown origin (FUO) from 1985 to 1989 were studied. Etiologic diagnoses were made in 117 (90%) patients, 60 (46.1%) patients had infections, 22 (16.9%) neoplasms, 19 (14.6%) connective tissue diseases, and 16(12.3%) various diseases grouped under "miscellaneous", 10% of the FUO cases remained undiagnosed and the death rate was 13.8%. This clinical analysis showed that infection was the most frequent cause of FUO in this series.

[Mediterranean spotted fever. A case report and review of literature]

A patient was documented as having mediterranean spotted fever by indirect immunofluorescence antibody test and inoculation of the patient's blood into the yolk sac of embryonated hen egg. In general, the infection of rickettsia conorii is caused by bite of infected tick. The infection in this case, however, occurred in a laboratory, so the transmitting route might be infected aerosol via impaired mucous membrane.