High Amounts Of Lactic Acid Research Articles

Increased expression of monocarboxylate transporters 1, 2, and 4 in colorectal carcinomas

Tumour cells are known to be highly glycolytic, thus producing high amounts of lactic acid. Monocarboxylate transporters (MCTs), by promoting the efflux of the accumulating acids, constitute one of the most important mechanisms in the maintenance of tumour intracellular pH. Since data concerning MCT expression in colorectal carcinomas (CRC) are scarce and controversial, the present study aimed to assess the expressions of MCT1, 2, and 4 in a well characterized series of CRC and assess their role in CRC carcinogenesis. CRC samples (126 cases) were analyzed for MCT1, MCT2, and MCT4 immunoexpression and findings correlated with clinico-pathological parameters. Expression of all MCT isoforms in tumour cells was significantly increased when compared to adjacent normal epithelium. Remarkably, there was a significant gain of membrane expression for MCT1 and MCT4 and loss of plasma membrane expression for MCT2 in tumour cells. Plasma membrane expression of MCT1 was directly related to the presence of vascular invasion. This is the larger study on MCT expression in CRC and evaluates for the first time its clinico-pathological significance. The increased expression of these transporters suggests an important role in CRC, which might justify their use, especially MCT1 and MCT4, as targets in CRC drug therapy.

Lactic acid, pyruvic acid and lactate/pyruvate ratio in the Anoplocephalid tapeworm Stilesia globipunctata infecting sheep ( Ovis aries)

Lactic acid content was found to vary among the different proglottid types of the parasite. This higher amount of lactic acid might be considered as the end product of anaerobic metabolism. The pyruvic acid level of the parasitic proglottides remained lower than lactate level. The intermediary carbohydrate metabolites, viz. lactate, pyruvate and the lactate/pyruvate ratio being indicators of high rate metabolism, their levels may notably infer the metabolic status of the parasite and also the interaction between the parasite species Stilesia globipunctata and the sheep host.

The H+-Linked Monocarboxylate Transporter (MCT1/SLC16A1): A Potential Therapeutic Target for High-Risk Neuroblastoma

Neuroblastomas produce high amounts of lactic acid and upregulate the H(+)-linked monocarboxylate transporter isoform 1 (MCT1/SLC16A1). We found elevated MCT1 mRNA levels in fresh neuroblastoma biopsy samples that correlated positively with risk of fatal disease and amplification of the "proto-oncogenic" transcription factor MYCN. We further investigated MCT as a potential therapeutic target in vitro. The neuroblastoma cell lines evaluated were Sk-N-SH, CHP134, IMR32, and NGP. All lines exhibited decreased intracellular pH at low tumor-like extracellular pH. Lonidamine or exogenous lactate further lowered intracellular pH. Immediate early lowering of intracellular pH with lonidamine or lactate at extracellular pH 6.5 correlated positively with diminished cell viability within 48 h. These findings indicate that MCT1 is a potential therapeutic target and that neuroblastoma therapy may be enhanced by therapeutic strategies to inhibit or overwhelm MCT. Additional experiments indicated that the mechanism of cell death by lonidamine or exogenous lactate is similar to that obtained using alpha-cyano-4-OH-cinnamate, a well established MCT inhibitor. Because lactate production is also high in melanoma and many other tumor types, MCT inhibitors may have broad application in cancer treatment. Such treatment would have selectivity by virtue of the acidic milieu surrounding tumors, because MCT is increasingly active as extracellular pH decreases below 7.0 and lactic acid production increases.

Optimization of Growth ofLactobacillus casei ASCC292 and Production of Organic Acids in the Presence of Fructooligosaccharide and Maltodextrin

ABSTRACT: Growth of Lactobacillus casei ASCC 292 was optimized in the presence of 2 prebiotics, namely fructooligosaccharide (FOS) and maltodextrin, and the patterns of organic acids produced was monitored. Perturbation plot, response surface, and coefficient estimates showed that inoculum size and concentration of prebiotics had significant quadratic effects on growth, with FOS showing the most prominent quadratic change. The second-order polynomial regression model estimated the optimum inoculum size and the concentrations of FOS and maltodextrin for the growth of L.casei ASCC 292 to be 1.67% w/v, 4.82% w/v, and 6.93% w/v, respectively.Validation experiments showed that the predicted optimum condition was better than the high and low levels of the factors, and at center points. Response surface methodology (RSM) was reliable in developing a model, optimizing factors, and analyzing interaction effects. Analysis of individual organic acids production by L. casei ASCC 292 showed that highest amount of lactic acid was produced, followed by propionic, acetic, formic, and butyric acid. The production of lactic acid was greatly influenced by the inoculum size, and the organism was relatively sensitive to the end-product of maltodextrin fermentation. Production of acetic acid was greatly influenced by the inoculum size and was inhibited by end-product of the maltodextrin fermentation. Increased concentration of FOS contributed to the increased production of propionic acid. The response surface of butyric and formic acid showed that the production of these acids were growth associated.

Microbiological and Biochemical Characterization of the Traditional Steeping Process of Waxy Rice for Yukwa (a Korean Oil-Puffed Snack) Production

Selected microbiological and biochemical characteristics of the steeping process for the production of yukwa, a traditional Korean oil-puffed snack made of waxy rice, were investigated during steeping of waxy rice in water for 15 days. The lengthy steeping process was largely predominated by lactic acid bacteria (LAB), particularly, Lactobacillus and Leuconostoc. The predominat type of bacterium isolated was the Y26 strain tentatively identified as Lactobacillus plantarum. The titratable acidity of the steeping medium increased from 0.01 to 1.13%, in parallel with the decrease in pH ranging from 6.3 to 4.2 as the steeping period increased from 0 to 15 days. A high amount of lactic acid and to a much lesser extent, butyric acid, acetic acid, propionic acid, and succinic acid were detected during the steeping process. The amount of reducing sugars in the steeping medium increased from 0.61 to 10.43 mg/mL, whereas sucrose decreased from 0.46 mg% to an undetectable level. Starch degradation products including glucose, maltose and oligosaccharides ranging G3-G7 were not initially noticed, but their content increased during the steeping process until completion. However, no oligosaccharides larger than G8 were detected in the steeping medium. The activities of α-amylase, β-amylase and protease in the steeping medium of waxy rice tended to rise increase with time during the steeping process. From these results, the lengthy steeping process in yukwa production can be characterized as the spontaneous fermentation, dominated by lactic acid bacteria, which is a necessary process for inducing biochemical modification of waxy rice.

Lactic acid-mediated suppression of Helicobacter pylori by the oral administration of Lactobacillus salivarius as a probiotic in a gnotobiotic murine model.

We examined whether or not the lactobacilli administered to treat Helicobacter pylori (H. pylori) infection can suppress the colonization of H. pylori, and we also sought to elucidate the mechanism of such suppression. We used an in vitro culture system and an H. pylori-infected gnotobiotic murine model. Among the lactobacillus species examined in vitro, Lactobacillus salivarius (L. salivarius) but not L. casei or L. acidophilus proved to be capable of producing a high amount of lactic acid and thus completely inhibiting the growth of H. pylori in a mixed culture. The validity of L. salivarius as a probiotic to suppress H. pylori and thus reduce the inflammatory response was again confirmed in vivo by using an H. pylori-infected gnotobiotic murine model. Based on our findings, L. salivarius was found to be a potentially effective probiotic against H. pylori.

Lactic acid-mediated suppression of Helicobacter pylori by the oral administration of Lactobacillus salivarius as a probiotic in a gnotobiotic murine model

Objectives: We examined whether or not the lactobacilli administered to treat Helicobacter pylori ( H. pylori) infection can suppress the colonization of H. pylori, and we also sought to elucidate the mechanism of such suppression. Methods: We used an in vitro culture system and an H. pylori-infected gnotobiotic murine model. Results: Among the lactobacillus species examined in vitro, Lactobacillus salivarius ( L. salivarius) but not L. casei or L. acidophilus proved to be capable of producing a high amount of lactic acid and thus completely inhibiting the growth of H. pylori in a mixed culture. The validity of L. salivarius as a probiotic to suppress H. pylori and thus reduce the inflammatory response was again confirmed in vivo by using an H. pylori-infected gnotobiotic murine model. Conclusion: Based on our findings, L. salivarius was found to be a potentially effective probiotic against H. pylori.

Technological and sensorial evaluation of Lactobacillus strains as starter cultures in fermented sausages

The performance of several lactobacilli strains isolated from naturally fermented sausages as starter cultures was evaluated. Microbiological, physical and chemical changes, in addition to sensorial aspects were studied. From the 12 different strains tested, 10 were capable of leading the fermentation in every batch throughout the process. The monitoring of the inoculated strains was easily carried out by plasmid profiles and by checking the pH rate drop of the sausages, which was slower for the non-inoculated lots. Treatment using natural fermentation resulted in a product where hydrogen sulphide odours, which could be related to the higher content of Enterobacteriaceae throughout the ripening process, diminished its overall acceptability. The lots seeded with different L. sake strains were found to be low in acid in sensory evaluation, correlating with a low lactic acid content. In contrast, the L. plantarum lot gave rise to an overacidified product related to having the highest amount of lactic acid at the end of the process. As a general rule lactobacilli strains isolated from meat origins are good candidates as starter cultures in the manufacture of dry-fermented sausages and produce satisfactory products depending on the specific strains used more than on the species.

Comparative studies of the degradation of grass fructan and inulin by strains of Lactobacillus paracasei subsp. paracasei and Lactobacillus plantarum

Four strains of Lactobacillus paracasei subsp. paracasei and Lact. plantarum are investigated within 16 d in order to determine the formation of metabolites during the degradation of grass fructan and inulin as well as the subsequent fermentation to lactic acid. The decrease of the total content of fructans throughout the entire time of investigation shows differences specific for strains as for either fructan substrate. The strain Lact. plantarum V 54/6 completely degrades the grass fructan and inulin within no longer than 13 d. The utilization of fructan by the other strains is temporally delayed, and in a smaller degree of degradation, especially remarkable for inulin cleavage. The structural modifications of decomposed fructans are characterized by a noticeable shift of the mean DP from approximately 80 to the oligomeric range analysed by anion exchange chromatography. Additionally, a newly formed series of peaks of oligomeric saccharides was detected during the degradation of grass fructan and inulin. Part of the fructose that is derived from cleavage of fructans is fermented immediately by the LAB strains into differently high amounts of lactic acid. The abundance of formed fructose is enriched in the medium to a varying extent, depending on the strain as well as the substrate used. From these results a number of fructan degradative enzymes in lactobacilli have been concluded to possibly vary their modes of regulation: strain specific exo‐ and endohydrolases with different activities against β‐2,1 and β‐2,6 linked fructan.