老鹳草鞣质类化合物的抗腹泻作用研究

对老鹳草总鞣质(HGT)的抗腹泻作用研究表明：HGT有较好的治疗腹泻作用，可减少番泻叶或蓖麻油所引起腹泻次数；并可显著抑制正常及推进功能亢进小鼠的墨水胃肠推进率。结果提示抑制胃肠推进运动是HGT止泻机理之一。     

Antibiotic-resistant soil bacteria in transgenic plant fields

Understanding the prevalence and polymorphism of antibiotic resistance genes in soil bacteria and their potential to be transferred horizontally is required to evaluate the likelihood and ecological (and possibly clinical) consequences of the transfer of these genes from transgenic plants to soil bacteria. In this study, we combined culture-dependent and -independent approaches to study the prevalence and diversity of bla genes in soil bacteria and the potential impact that a 10-successive-year culture of the transgenic Bt176 corn, which has a blaTEM marker gene, could have had on the soil bacterial community. The bla gene encoding resistance to ampicillin belongs to the beta-lactam antibiotic family, which is widely used in medicine but is readily compromised by bacterial antibiotic resistance. Our results indicate that soil bacteria are naturally resistant to a broad spectrum of beta-lactam antibiotics, including the third cephalosporin generation, which has a slightly stronger discriminating effect on soil isolates than other cephalosporins. These high resistance levels for a wide range of antibiotics are partly due to the polymorphism of bla genes, which occur frequently among soil bacteria. The blaTEM116 gene of the transgenic corn Bt176 investigated here is among those frequently found, thus reducing any risk of introducing a new bacterial resistance trait from the transgenic material. In addition, no significant differences were observed in bacterial antibiotic-resistance levels between transgenic and nontransgenic corn fields, although the bacterial populations were different.     

比较基因组学在细菌分子进化领域的研究进展

在后基因组时代，比较基因组学已经成为诠释遗传信息生物学意义的重要方法。运用生物信息学的手段，比较分析不同细菌的基因组，我们逐步揭示了细菌染色体物理结构的保守性和基因内容多样性的产生机制。进化生物学家们正试图从基因组数据库中挖掘能够代表物种进化关系的具有普遍适用性的分子线索，重建生命进化树。     

Reexamining treatment of high-grade T1 bladder cancer according to depth of lamina propria invasion: a prospective trial of 200 patients

Background:

Management of high-grade T1 (HGT1) bladder cancer represents a major challenge. We studied a treatment strategy according to substaging by depth of lamina propria invasion.

Methods:

In this prospective observational cohort study, patients received initial transurethral resection (TUR), mitomycin-C, and BCG. Subjects with shallower lamina propria invasion (HGT1a) were followed without further surgery, whereas subjects with HGT1b received a second TUR. Association of clinical and histological features with outcomes (primary: progression; secondary: recurrence and cancer-specific survival) was assessed using Cox regression.

Results:

Median age was 71 years; 89.5% were males, with 89 (44.5%) cases T1a and 111 (55.5%) T1b. At median follow-up of 71 months, disease progression was observed in 31 (15.5%) and in univariate analysis, substaging, carcinoma in situ, tumour size, and tumour pattern predicted progression. On multivariate analysis only substaging, associated carcinoma in situ, and tumour size remained significant for progression.

Conclusions:

In HGT1 bladder cancer, the strategy of performing a second TUR only in T1b cases results in a global low progression rate of 15.5%. Tumours deeply invading the lamina propria (HGT1b) showed a three-fold increase in risk of progression. Substaging should be routinely evaluated, with HGT1b cases being thoroughly evaluated for cystectomy. Inclusion in the TNM system should also be carefully considered.     

Genomics of Streptococcus salivarius,a major human commensal

The salivarius group of streptococci is of particular importance for humans. This group consists of three genetically similar species, Streptococcus salivarius, Streptococcus vestibularis and Streptococcus thermophilus. S. salivarius and S. vestibularis are commensal organisms that may occasionally cause opportunistic infections in humans, whereas S. thermophilus is a food bacterium widely used in dairy production. We developed Multilocus sequence typing (MLST) and comparative genomic analysis to confirm the clear separation of these three species. These analyses also identified a subgroup of four strains, with a core genome diverging by about 10%, in terms of its nucleotide sequence, from that of S. salivarius sensu stricto. S. thermophilus species displays a low level of nucleotide variability, due to its recent emergence with the development of agriculture. By contrast, nucleotide variability is high in the other two species of the salivarius group, reflecting their long-standing association with humans. The species of the salivarius group have genome sizes ranging from the smallest (∼1.7 Mb for S. thermophilus) to the largest (∼2.3 Mb for S. salivarius) among streptococci, reflecting genome reduction linked to a narrow, nutritionally rich environment for S. thermophilus, and natural, more competitive niches for the other two species. Analyses of genomic content have indicated that the core genes of S. salivarius account for about two thirds of the genome, indicating considerable variability of gene content and differences in potential adaptive features. Furthermore, we showed that the genome of this species is exceptionally rich in genes encoding surface factors, glycosyltransferases and response regulators. Evidence of widespread genetic exchanges was obtained, probably involving a natural competence system and the presence of diverse mobile elements. However, although the S. salivarius strains studied were isolated from several human body-related sites (all levels of the digestive tract, skin, breast milk, and body fluids) and included clinical strains, no genetic or genomic niche-specific features could be identified to discriminate specific group.     

The effect of interleukin-1 (IL-1) on androgen metabolism in human gingival tissue (HGT) and periodontal ligament (PDL)

Abstract Due to the potent anabolic effects of the androgenic metabolite 5α-dihydrotestosterone (DHT) on matrix synthesis by connective tissue and bone, it was pertinent to investigate the effects of interleukin-1 (IL-1) on androgen metabolism by chronically inflamed human gingival tissue (HGT) and periodontal ligament (PDL). Duplicate incubations of HGT and PDL derived from 6 subjects (age- and sex-matched) were performed in Eagle's MEM+FCS with 14C-testosterone to study baseline conversion to DHT and 4-androstenedione. Similarly further incubations were performed for 24 h in a 5% CO₂ in air incubator, with HGT and PDL from 4 comparable patients to study the effect of IL-1 on this conversion. The medium was extracted radioactive metabolites separated by thin-layer chromatography and quantified. When baseline metabolism of HGT was compared with that of PDL. both tissues metabolised 14C-testosterone to DHT and 4-androstenedione. There was a 2.4-fold increase in DHT synthesis by PDL over that of HGT (n=6; p<0.005) and a 2.5-fold increase in 4-androstene-dione formation by PDL compared with HGT (n=6; p<0.01). In response to IL-1, HGT demonstrated a 2-fold increase in DHT synthesis (n=4; p<0.005) and a 3.5-fold increase in 4-androstenedione formation (p<0.01) over control gingival tissue; PDL showed a 9-fold increase in DHT synthesis in response to IL-1 (n=4; p<0.005) and a 6-fold increase in 4-androstenedione formation (p<0.005) over control ligament tissue. The increased androgen metabolic capacity of PDL over HGT, both at baseline and in response to IL-1 is in keeping with protein studies and may be relevant to repair processes during inflammatory periodontal disease.