Intraoperative lactic acid concentration during liver transplantation and cutoff values to predict early mortality: a retrospective analysis of 3,338 cases

Background: We aimed to explore intraoperative lactic acid (LA) level distribution during liver transplantation (LT) and determine the optimal cutoff values to predict post-LT 30-day and 90-day mortality.Methods: Intraoperative LA data from 3,338 patients were collected between 2008 to 2019 and all-cause mortalities within 30 and 90 days were retrospectively reviewed. Of the three LA levels measured during preanhepatic, anhepatic, and neohepatic phase of LT, the peak LA level was selected to explore the distribution and predict early post-LT mortality. To determine the best cutoff values of LA, we used a classification and regression tree algorithm and maximally selected rank statistics with the smallest P value.Results: The median intraoperative LA level was 4.4 mmol/L (range: 0.5–34.7, interquartile range: 3.0–6.2 mmol/L). Of the 3,338 patients, 1,884 (56.4%) had LA levels > 4.0 mmol/L and 188 (5.6%) had LA levels > 10 mmol/L. Patients with LA levels > 16.7 mmol/L and 13.5–16.7 mmol/L showed significantly higher 30-day mortality rates of 58.3% and 21.2%, respectively. For the prediction of the 90-day mortality, 8.4 mmol/L of intraoperative LA was the best cutoff value.Conclusions: Approximately 6% of the LT recipients showed intraoperative hyperlactatemia of > 10 mmol/L during LT, and those with LA > 8.4 mmol/L were associated with significantly higher early post-LT mortality.

Effects of Megasphaera elsdenii supplementation on fermentation and lactic acid concentration in the rumen: A meta-analysis of in vivo experiments

This study evaluated the effects of supplementation M. elsdenii on rumen fermentation and lactic acid concentration in vivo by integrating data from various related studies using a meta-analysis. A database was developed by integrating data from 72 treatments that originated from 17 articles. The parameters integrated were lactic acid concentration, fermentation products, and rumen microbial population. The database compiled was statistically analyzed using a mixed model methodology. Different studies were considered as random effects, and the doses of M. elsdenii were treated as fixed effects. The significance of an effect was stated when its p-value was <0.05. Results showed that supplementation of M. elsdenii linearly reduced lactic acid concentration (P=0.048), proportion of acetate (P=0.045), acetate: propionate ratio (P=0.043) and methane production (P<0.01). In addition, M. elsdenii supplementation also had a significant quadratic effect to increase total VFA (P<0.01) and linearly with pH (P<0.01), proportion of propionate (P=0.037), and valerate proportion (P=0.037). However, supplementation of M. elsdenii did not significantly affect (P>0.05) isobutyrate, isovalerate proportion, and protozoa population in the rumen. It can be concluded that M. elsdenii supplementation is proven to reduce lactic acid concentration, maintain rumen pH, reduce methane production and increase some rumen fermentation products.

Effects of Vanillic Acid on Dynamic Fermentation Parameter, Nitrogen Distribution, Bacterial Community, and Enzymatic Hydrolysis of Stylo Silage

Vanillic acid (VA) is a phenolic acid derivative commonly found in plants and foods, with a pleasant creamy odor and pharmacologic activities, which is hypothesized to help improve silage fermentation. The silage profile of stylo silage ensiled with addition of VA was evaluated. The results showed that VA addition resulted in the decrease of pH value (5.22 vs. 4.33), dry matter loss (5.37 vs. 2.51% DM), and ammonia-N proportion (14.57 vs. 1.51% CP) of stylo silage as well as the increase of lactic acid concentration (0.51 vs. 1.17% DM), true protein proportion (51.18 vs. 58.47% CP), and saccharification yield (113.64 vs. 126.40 mg/g DM). Meanwhile, bacterial community of stylo silage was altered, where the relative abundance of Enterobacter, Clostridium, and Kosakonia decreased and that of Commensalibacter and Methylobacterium increased. In conclusion, it is suggested that VA could be used as a novel silage additive to improve silage fermentation and nutrient preservation of stylo silage.

Neural network modeling of change in lactic acid concentration during continuous fermentation of bifidobacteria

In this work the changes in the lactic acid concentration during continuous fermentation of bifidobacteria have been investigated to obtain a neural network mathematical description. The fermentation was carried out under the conditions close to those of the descending colon (maintaining pH of 6.8 with 20% sodium hydroxide; anaerobiosis; the medium dilution rate was 0.04 h-1). This colon section is characterized by a large number of microorganisms, as well as their enormous influence on the host organism. The researches were carried out with the probiotic strain of Bifidobacterium adolescentis VKPM Ac-1662 (ATCC 15703T), the concentrations of the prebiotic oligofructose were varied (2, 5, 10, 15 g/l). Until a dynamic equilibrium state and at least 36 h after that, the concentrations of lactic and acetic acids using the of high performance liquid chromatography, optical density and viable bacteria count (CFU/ml) were measured. The neural network was trained on the basis on the obtained experimental data. The multilayer perceptron was chosen as the main architecture of the neural network. The vectors of the training sample include 6 variables: 5 input and 1 output. The training took place synchronously using the error back propagation method. The general error of the neural network was 1.85%. It was proved that the neural network approach helps to well illustrate the influence of various factors on the course of biotechnological processes; it summarizes the multiple experimental data with an acceptable error. The resulting neural network mathematical description proves that the representativeness of the training sample is important for obtaining the most accurate mathematical description. Further researches are needed to obtain a mathematical description of the change in the all environment components concentration in the form of a complex of the trained artificial neural networks.

A Novel Dairy Fermented Frozen Dessert with Honey and Pomegranate Juice: Physicochemical, Rheological and Sensory Properties

The effect of fat content and added yoghurt, honey and pomegranate juice concentration on the overrun, and the physicochemical, rheological and sensory properties of frozen yoghurt samples was investigated, aiming in the production of a novel low-fat and functional dairy fermented frozen dessert. For this purpose, the methodology of mixture experiment was applied to twenty samples, while a control sample (without using honey and pomegranate juice) was also produced. According to the results, the increase in yoghurt concentration resulted in increasing pH, overrun, brightness, elastic modulus (G&acute;) determined at -2 &deg;C and sensory hardness of the samples, while it reduced color parameters a* and b*, creaminess, sweetness and fattiness. Increasing honey concentration reduced lactic acid concentration, G&acute; at -2 &deg;C, hardness, sensory acidity, and to a lesser extent pH, while increased color parameter b*, overrun, sensory color intensity, creaminess, sweetness, and fattiness of the samples. The increase in pomegranate juice concentration resulted in decreasing pH, brightness and b*, as well as increasing a*, color intensity, creaminess and sensory acidity. Finally, fat, by interacting with one or two of the three constituents (yoghurt, honey and pomegranate juice), decreased pH, creaminess and fattiness, while increased lactic acid concentration, b*, color intensity and to a lesser degree the overrun level of the samples. Overall acceptability of the samples indicated that it is possible to use honey and pomegranate juice in the production of low-fat frozen yoghurt with favorable sensory properties.

Effects of Sodium Formate and Calcium Propionate Additives on the Fermentation Quality and Microbial Community of Wet Brewers Grains after Short-Term Storage

The objective of this research was to examine the effect of sodium formate (SF) and calcium propionate (CAP) on the fermentation characteristics and microbial community of wet brewers grains (WBG) after short-term storage. In the laboratory environment, fresh WBG was ensiled with (1) no additive (CON), (2) sodium formate (SF, 3 g/kg fresh weight), and (3) calcium propionate (CAP, 3 g/kg fresh weight) for 20 days. After opening, fermentation characteristics, chemical composition, rumen effective degradability, and the microbial community of ensiled WBG were analyzed. The addition of CAP had no effect on pH and lactic acid concentration and increased the concentrations of propionic acid; the SF group had the lowest pH and acetic acid, butyric acid, and ammonia nitrogen contents and the highest lactic acid concentration. After fermentation, the SF group had the highest contents of dry matter (DM), water-soluble carbohydrates (WSCs), and neutral detergent fiber (NDF). The contents of the three nutrients in the CAP group were significantly higher than those in the CON group. The addition of the two additives had little influence on the crude protein (CP) and acid detergent fiber (ADF) contents of the ensiled WBG. Two additives elevated in situ effective degradability of DM and NDF compared with the parameters detected in the CON group; WBG ensiled with SF had higher effective in situ CP degradability than that in the CON and CAP groups. The results of the principal component analysis indicate that the SF group and two other groups had notable differences in bacterial composition. The analysis of the genus level of the bacterial flora showed that the content of Lactobacillus in the SF group was significantly higher than that in the two other treatment groups, while the content of Clostridium was significantly lower than that in the two other treatment groups. Therefore, the addition of sodium formate can suppress the undesirable microorganisms, improve the fermentation qualities, and ensure that WBG is well preserved after 20 days of ensiling.