Minimizing enzyme mass to decompose flux distribution for identifying biologically relevant elementary flux modes.

The flux distribution in metabolic network can be decomposed as non-negative linear combinations of elementary flux modes (EFMs). Identifying biologically relevant EFM combination by decomposing flux distribution in metabolic network is a useful method to study metabolisms in systems biology. However, the occurrence of biologically irrelevant EFMs hinders the application of such methods. In this paper, we introduce a novel method for identifying EFM combination by minimizing enzyme mass. Our proposed method, called EMMD (Enzyme Mass Minimization Decomposition), takes into consideration both thermodynamic and enzymatic constraints in stoichiometry metabolic models. By implementing EMMD, we can decompose the flux distributions in metabolic network to detect biologically relevant EFM combinations. We demonstrate the effectiveness of our method by applying it to the core Escherichia coli metabolic network and show that the optimal EFM combinations identified by EMMD are unique. Moreover, the optimal EFM combination identified by EMMD not only aligns more closely with experimental values in terms of estimated growth rate, but it also demonstrates more favorable thermodynamics. Finally, we investigated the growth of the core Escherichia coli metabolic network in Luria-Bertani medium containing different carbon sources, revealing the impact of various carbon sources on the growth rate of flux distribution. EMMD thus could be a promising complement to the existing flux decomposition tools.

Ligature induced periodontitis in rats causes gut dysbiosis leading to hepatic injury through SCD1/AMPK signalling pathway.

AIMS: Previous studies have demonstrated that chronic periodontitis (CP) is closely associated with the occurrence and development of a variety of systemic diseases. In this study, we successfully constructed a rat CP model through dental silk ligation, and the corresponding inflammatory reactions and fatty lesions were observed in the liver. MAIN METHODS: Sprague-Dawley rats (n = 6) underwent tooth ligation at the bilateral first molars with silk thread to induce CP and were sacrificed 8 weeks later and compared to non-ligated rats (n = 6). RNA sequencing and 16S rRNA analysis were performed to determine the molecular mechanisms of CP involved in inducing liver disease. Alveolar bone loss, liver enzymes, mandible and liver histopathology, and inflammatory responses were compared between groups. KEY FINDINGS: RNA sequencing of liver tissue showed that the expression of SCD1 increased significantly in CP rats compared to controls. KEGG enrichment analysis showed that the AMPK signalling pathway may be involved in liver steatosis. The intestinal flora of faecal samples of rats were analysed by 16S rRNA sequencing, and the results indicated that the intestinal flora of the CP group was evidently imbalanced. The expression levels of tight junction proteins (ZO-1, occludin, and claudin-1) were significantly reduced in CP rats. Meanwhile, increases in serum IL-1ß and lipopolysaccharide in CP rats reflected a systemic inflammatory response. SIGNIFICANCE: CP may be involved in the occurrence and development of hepatic injury and liver steatosis, and its mechanism may be related to the oral-gut-liver axis and SCD1/AMPK signal activation in the liver.

Diagnostic accuracy of quantitative fetal fibronectin to predict spontaneous preterm birth: A meta-analysis.

BACKGROUND: Use of quantitative fetal fibronectin (fFN) testing to predict spontaneous preterm birth (sPTB) is gaining attention owing to its absolute measurement of fFN concentration and increased positive predictive value compared with qualitative testing. OBJECTIVE: To assess the predictive values of quantitative fFN for sPTB in different predefined thresholds using systematic review and meta-analysis. SEARCH STRATEGY: Five major databases (PubMed, ScienceDirect, Web of Science, Embase, Cochrane library) were searched for eligible studies. SELECTION CRITERIA: Observational studies of the diagnostic accuracy of different quantitative fFN thresholds on delivery outcomes were included. DATA COLLECTION AND EXTRACTION: Articles were reviewed independently by two authors and data were extracted. Sensitivity, specificity, diagnostic odds ratio, and summary receiver operating characteristic curves were extracted and calculated. MAIN RESULTS: Fifteen studies were included. To detect sPTB at less than 34 weeks of gestation, pooled sensitivities for thresholds of 10, 50, 200, and 500 ng/ml were 0.78, 0.56, 0.33, and 0.11, respectively. Pooled specificities were 0.63, 0.84, 0.96, and 0.99, respectively. CONCLUSIONS: Based on the results of the meta-analysis, the threshold of 10 ng/ml fFN may be a new choice for the prediction of sPTB. The improved diagnostic accuracy of quantitative testing over qualitative testing can provide additional discriminatory information for clinical practice.

Experimental Study on the Explosion Characteristics of CH4/O2/N2 Mixtures with Different Oxygen Enrichment Coefficients and Ignition Positions.

In this paper, the flame propagation characteristics and overpressure oscillation characteristics of CH4 explosion were studied under different ignition positions (IPs) and oxygen enrichment conditions in a half-open tube. The distances between the IP and the closed end of the tube are 0, 250, 500, and 750 mm. The oxygen enrichment coefficient (φ) values used in the experiment are 0.21, 0.3, and 0.4. The experimental results show that the IP and oxygen enrichment coefficient have an important influence on the flame structure and overpressure oscillation. Only when the oxygen enrichment coefficient φ = 0.21, a tulip flame will be formed. The IP close to the outlet can make the air participate in the combustion more quickly. With the increase of the oxygen enrichment coefficient, the combustion-induced rapid phase transition phenomenon is more likely to occur, and the maximum overpressure value and the overpressure rise rate of flame will increase. It is worth noting that after increasing the oxygen enrichment coefficient, the IP has less influence than the oxygen enrichment coefficient on the overpressure rise rate.

Evaluation of tracheobronchial branching abnormalities in patients with microtia using chest computed tomography.

BACKGROUND: The objective of this study was to identify the characteristics and incidence of Tracheobronchial branching abnormalities in patients with microtia and to evaluate the risk of anesthesia. METHODS: A total of 204 consecutive microtia patients and 465 nose cosmetic patients without microtia received a preoperative chest computed tomography. A retrospective study was performed with the clinical and imaging data from July 2016 to April 2017. RESULTS: With the chest computed tomography images, a total of 7 cases were documented with Tracheobronchial branching abnormalities, including 6 cases among the microtia patients and 1 case among the cosmetic patients without microtia. The incidence of Tracheobronchial branching abnormalities was higher in microtia patients than the cosmetic patients without microtia (2.94% versus 0.22%, P < 0.01). CONCLUSIONS: The incidence of Tracheobronchial branching abnormalities was high in patients with microtia. Preoperative diagnosis of tracheal bronchus can help anesthesiologists avoid complications. Microtia with Tracheobronchial branching abnormalities may involve a new syndrome previously undiscovered or just another extension with the very wide spectrum of microtia.

A new strategy for total auricular reconstruction using prelamination of an extended retroauricular flap with tissue expansion.

BACKGROUND AND AIM: To accomplish total ear reconstruction with aesthetic appearance is a great challenge for plastic surgeons worldwide due to insufficient skin coverage. A retroauricular fascial flap and skin graft technique are commonly used, but the results obtained are not satisfactory due to color mismatch, severe edema, and donor-site morbidity. Here, we describe a novel strategy for total ear reconstruction, utilizing an extended retroauricular flap prelaminated with tissue expansion to obtain enough skin for ear reconstruction. METHODS: About 2 months before ear reconstruction, a kidney-shaped tissue expander was inserted at the mastoid region subcutaneously. The retroauricular skin became enlarged and thinner in 2 months after expansion. Next, the expander was removed and the retroauricular flap was extended by dissecting the surrounding scalp subcutaneously. By mobilizing the scalp-extended retroauricular flap, we could encapsulate the entire framework with thin and non-hair-bearing skin. RESULTS: From August 2014 to September 2015, 36 microtia patients had undergone ear reconstruction using the novel strategy. Satisfactory aesthetics along with fine structure, symmetry, and maintenance of the auriculocephalic angle was achieved in all patients. CONCLUSIONS: Using our novel strategy, we can obtain satisfactory aesthetic outcomes by fully mobilizing the expanded skin without additional morbidities of the donor sites. Patients are satisfied with the vivid ear contour and lack of groin scar.