BACKGROUNDStreptococcus (S.) oligofermentans is a newly identified bacteria with a yet to be defined mechanism of sucrose metabolism that results in acid production. This study aimed to investigate the biochemical mechanisms of S. oligoferm-entans glucose metaolism.

METHODSThe S. oligofermentans LMG21532, Lactobacillus (L.) fermentum 38 and the S. mutans UA140 were used to characterize sucrose metabolism by measuring lactate dehydrogenase (LDH) activity and lactic acid production. Continuous dynamics and high performance capillary electrophoresis were used to determine LDH activity and lactic acid production, respectively, from bacteria collected at 0, 10 and 30 minutes after cultured in 10% sucrose.

RESULTSThese analyses demonstrated that LDH activity of the three bacterial strains examined remained stable but significantly different throughout the sucrose fermentation process. The S. oligofermentans LDH activity ((0.61 ± 0.05) U/mg) was significantly lower than that of L. fermentum ((52.91 ± 8.97) U/mg). In addition, the S. oligofermentans total lactate production ((0.048 ± 0.021) mmol/L) was also significantly lower than that of L. fermentum ((0.958 ± 0.201) mmol/L). Although the S. oligofermentans LDH production was almost double of that produced by S. mutans ((0.32 ± 0.07) U/mg), lactic acid production was approximately one sixth that of S. mutans ((0.296 ± 0.058) mmol/L). Additional tests examining pyruvic acid production (the LDH substrate) demonstrated that lactic acid concentrations correlated with pyruvic acid production. That is, pyruvic acid production by S. oligofermentans was undetectable following sucrose incubation, however, (0.074 ± 0.024) and (0.175 ± 0.098) mmol/L pyruvic acid were produced by S. mutans and L. fermentum, respectively.

CONCLUSIONS. oligofermentans is incapable of fermenting carbohydrates to produce enough pyruvic acid, which results in reduced lactic acid production.

L-Lactate Dehydrogenase ; metabolism ; Lactic Acid ; metabolism ; Pyruvic Acid ; metabolism ; Streptococcus ; metabolism ; Sucrose ; metabolism

Lactic acid has a wide range of uses in the chemical, pharmaceutical and food industry. With rapid development of poly (lactic acid) industry, the demand for polymer-grade L-lactic acid is continuously increasing. Developing low-cost, non-food-biomass-lactic-acid fermentation process and the fermentation-separation coupled technology are trends to reduce polymer-grade L-lactic acid production cost. This review summarized the most recent advances in low-cost L-lactic acid fermentation based on the use of non-food biomass, followed by addressing the key issue that might be strategically important for future development of polymer-grade L-lactic acid production in industry.
Biomass ; Biotechnology ; trends ; Cellulose ; metabolism ; Fermentation ; Insulin ; metabolism ; Lactic Acid ; metabolism ; Manihot ; metabolism ; Polymers ; metabolism

Tumor cells have unique energy metabolism phenomena, namely high glucose absorption, aerobic glycolysis and high lactic acid production, which are characterized by down-regulation of related proteins involved in oxidative metabolism in tumor cells, and up-regulation of glucose transporters and monocarboxylate transporters. Studies have shown that drugs that target tumor cell glucose metabolism have the ability to selectively kill tumor cells, bringing new hope for tumor treatment. Tumor stem cells are considered to be the root cause of tumor recurrence, metastasis and poor prognosis, and their energy metabolism characteristics have not yet been agreed. Studies have shown that reversing the energy metabolism of tumor stem cells can increase their chemosensitivity. This article reviews recent studies on tumor and tumor stem cell glucose metabolism and the opportunities and challenges of tumor treatment through targeting glucose metabolism, which might provide new ideas and opportunities for clinical tumor therapy.
Energy Metabolism ; Glucose ; metabolism ; Glycolysis ; Humans ; Lactic Acid ; metabolism ; Neoplasms ; metabolism ; Neoplastic Stem Cells ; metabolism

Localized, water-suppressed in vivo 'H MRS was performed to evaluated the proton metabolic alterations in patients with acute cerebral infarction.Ten brain infarction patients(six males and four females; age range 53-77) participated in this study. GE Signa 1.5-T whole-body NMI/MRS system using STEAM pulse sequence was used. Voxels were selected from the cerebral infarcted region and contralateral normal region as control in the same patient. Proton metaboliteratiosrelativetocreatine (Cr) wereobtainedusingaMa-rquartalgorithm. The specific features in the cerebral infarcted regions demonstrated a significant decrease of N-acetyl aspartate (NAA)/creatine (Cr) ratio, compared with control regions. Markedly increased lactate (Lac) level was observed in areas of cerebral infarctioln in all patients. Our preliminary study showed that NAA/Cr ratio in the infarcted regions was substanially different from that in control regions.The signal intensity of Lac may be served as a metabolic criterion that can specify acuteness of infarction, and also evaluate the therapeutic effect. It is necessary to investigate the spectral alterations in various stages of cerebral infarction for further detail analysis.
Aspartic Acid ; Brain Infarction ; Cerebral Infarction* ; Female ; Humans ; Infarction ; Lactic Acid ; Male ; Metabolism ; Protons ; Steam

The key to the treatment of septic shock is to provide adequate oxygen supply and improve tissue perfusion. Lactate and central venous oxygen saturation (ScvO) are commonly used as the indices of oxygen metabolism, but tissue hypoxia may still exist even when lactate and ScvOare within the normal range. Arteriovenous difference in carbon dioxide partial pressure (COgap) can accurately reflect oxygen delivery when ScvOis in the normal range. This article reviews the advantages and shortages of lactate, lactate clearance rate, ScvO, and COgap in evaluating tissue hypoxia, in order to provide a reference for treatment and severity evaluation of septic shock.
Carbon Dioxide ; blood ; Humans ; Lactic Acid ; metabolism ; Metabolic Clearance Rate ; Oxygen ; blood ; Shock, Septic ; metabolism

In order to carry out the process of the repeated intermittent L-lactic acid fermentation by self-immobilized Rhizopus oryzae, we investigated the effect of medium compositions on the morphology of Rhizopus oryzae. In submerged culture, fungi can be grown as broths of freely suspended mycelia and pellets or clumps, the pellets can be immobilized by themselves. The optimum medium composition for the first patch of fermentation was: 120 g/L glucose, 3 g/L NH4NO3, 0.14 g/L KH2PO4, 0.16 g/L NaH2PO4 (the concentration ratio of K+ and Na+ was 1:1). After 72 h fermentation, the physical form of Rhizopus oryzae was mostly uniform pellet with the diameter of 1.0-2.0 mm, the concentration of L-lactic acid was 100.8 g/L, and the conversion rate of glucose was 84%. During 16 batches of repeated fermentation, the L-lactic acid level was above 60.0 g/L and the conversion rate of glucose was 75%. The fermentation time of every batch was 24 h.
Cells, Immobilized ; metabolism ; Culture Media ; Fermentation ; Lactic Acid ; biosynthesis ; Rhizopus ; growth & development ; metabolism

The aim of this paper is to explore the prevention of rabbit postoperative abdominal cavity adhesion with poly (lactic-co-glycotic acid) (PLGA) membrane and the mechanism of this prevention function. Sixty-six Japanese white rabbits were randomly divided into normal control group, model control group and PLGA membrane group. The rabbits were treated with multifactor methods to establish the postoperative abdominal cavity adhesion models except for those in the normal control group. PLGA membrane was used to cover the wounds of rabbits in the PLGA membrane group and nothing covered the wounds of rabbits in the model control group. The hematologic parameters, liver and kidney functions and fibrinogen contents were detected at different time. The rabbit were sacrificed 1, 2, 4, 6, 12 weeks after the operations, respectively. The adhesions were graded blindly, and Masson staining and immunohistochemistry methods were used to observe the proliferation of collagen fiber and the expression of transforming growth factor β1 (TGF-β1) on the cecal tissues, respectively. The grade of abdominal cavity adhesion showed that the PLGA membrane-treated group was significant lower than that in the model control group, and it has no influence on liver and kidney function and hematologic parameters. But the fibrinogen content and the number of white blood cell in the PLGA membrane group were significant lower than those of model control group 1 week and 2 weeks after operation, respectively. The density of collagen fiber and optical density of TGF-β1 in the PLGA membrane group were significant lower than those of model control group. The results demonstrated that PLGA membrane could be effective in preventing the abdominal adhesions in rabbits, and it was mostly involved in the reducing of fibrinogen exudation, and inhibited the proliferation of collagen fiber and over-expression of TGF-β1.
Abdominal Cavity ; surgery ; Animals ; Collagen ; metabolism ; Lactic Acid ; Polyglycolic Acid ; Rabbits ; Tissue Adhesions ; prevention & control ; Transforming Growth Factor beta1 ; metabolism

Fermentative production of lactic acid, an important bio-based chemicals, has made considerable progress. In addition to the food industry and production of polylactic acid, lactic acid also can be used as an important platform chemical for the production of acrylic acid, pyruvic acid, 1,2-propanediol, and lactic acid esters. This article summarizes the recent progress in biocatalytic production of lactic acid derivatives by dehydration, dehydrogenation, reduction, and esterification. Trends in the biotransformation of lactic acid are also discussed.
Acrylates ; metabolism ; Bacteria ; genetics ; metabolism ; Biotechnology ; methods ; Biotransformation ; Fermentation ; Industrial Microbiology ; methods ; Lactic Acid ; metabolism ; Propylene Glycol ; metabolism ; Pyruvic Acid ; metabolism ; Yeasts ; genetics ; metabolism

BACKGROUND AND OBJECTIVES: Recent reports suggest that brief periods of low-flow ischemia (lf Isc) and reperfusion (R) before prolonged Isc mimic ischemic preconditioning (IPC) in murine hearts, probably by a preservation of high energy phosphates. MATERIALS AND METHODS: In order to test this hypothesis, Langendorff-perfused isolated rabbit hearts were subjected to 45 min lf Isc (5% of baseline perfusion flow) with lf IPC or not, followed by 120 min R. lf IPC was induced by a single episode of 5 min lf Isc and 10 min R. These were compared with IPC hearts by 5 min no-flow Isc and 10 min R. RESULTS: lf IPC as well as IPC enhanced post-ischemic functional recovery although IPC did not reduce infarct size (Isc control, 37.5+/-3.1, IPC, 16.2+/-1.5, lf Isc, 43.0+/-0.7, and lf IPC, 40.4+/-1.0% of the left ventricle). Myocardial ATP hydrolysis and lactate production during the preischemic, ischemic, and reperfusion periods were not differ between the experimental groups. CONCLUSION: These results suggest that a brief period of lf Isc could not precondition the rabbit heart and the energy metabolism hypothesis may not be a universal mechanism for the cardioprotective effect of IPC.
Adenosine Triphosphate ; Energy Metabolism ; Heart ; Hydrolysis ; Ischemia ; Ischemic Preconditioning ; Lactic Acid ; Myocardial Infarction ; Perfusion* ; Phosphates ; Reperfusion

Human K562 leukemia cells were cultured under free and microencapsulated condition, respectively. The cell cycles in the two kinds of cultures were investigated by flow cytometry. Moreover, mathematical model was established to simulate the cell viability and metabolized characteristic in different cultures. It was found that the cell percent in S phase was higher and the cell viability was better when cultured in microcapsule than that in free culture. The results showed that the model successfully described the substrate consumption and product formation in microencapsulated culture as well as in suspension culture. Based on the model, it was indicated that not only there was a higher proliferation and metabolic activity but also the time of the high activity could keep longer in microencapsulated culture. The parameters of the model showed that there was no significant difference between the two kinds of cultures when the influence of the glucose on the cell viability was concerned (kA(free) approximately = kA (APA)) but lactate had a obvious suppression effect on cell viability in free culture, and neglectable suppression in microencapsulated culture (kL(free) > kL(APA)).
Cell Culture Techniques ; methods ; Cell Cycle ; Cell Proliferation ; Humans ; K562 Cells ; Lactic Acid ; metabolism ; Models, Biological