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PubMed1980

Measurement of lactic acid in pleural fluid.

Lactic acid (LA) concentrations in the pleural fluid of 75 patients were determined by the Monotest Lactate Kit (MLK). Lactic acid values in 18 cases of bacterial or tuberculous pleural infection were strikingly higher (mean 81 mg%, range 45-200 mg%), than in 42 cases with pleural effusion due to congestive heart failure, hepatic cirrhosis, nephrosis, trauma, and systemic lupus erythematosus (SLE; mean 19 mg%, range 6-47 mg/). High levels of LA were also found in the pleural fluid of 15 patients with malignancy of pleural cavity. Determination of LA can be an additional rapid tool in the differentiation between bacterial pleural inflammation and pleural effusion of various forms except in cases with malignancy of the pleural cavity.

Adolescent↗
PubMed2000

Fermentation of fructooligosaccharides by lactic acid bacteria and bifidobacteria.

Lactic acid bacteria and bifidobacteria were screened of their ability to ferment fructooligosaccharides (FOS) on MRS agar. Of 28 strains of lactic acid bacteria and bifidobacteria examined, 12 of 16 Lactobacillus strains and 7 of 8 Bifidobacterium strains fermented FOS. Only strains that gave a positive reaction by the agar method reached high cell densities in broth containing FOS.

Bifidobacterium↗
PubMed1996

Immunomodulatory activity of beta-casein permeate medium fermented by lactic acid bacteria.

During fermentation, lactic acid bacteria may be able to release components that possess immunomodulatory activity. This activity was investigated in several culture supernatants arising from lactic acid bacteria cultured in a medium composed primarily of UF permeate of bovine milk; beta-CN was added as the sole protein source. Only a Lactobacillus helveticus supernatant allowed the modulation (both suppression and enhancement) of lymphocyte proliferation in vitro on human peripheral blood lymphocytes, but L. helveticus did not modulate the cytotoxic activity of natural killer cells or of lymphokine-activated killer cells. The addition of different quantities of culture supernatant to cultures of human mononuclear cells, stimulated by the mitogen concanavalin A, significantly increased the production of interferon-gamma and decreased the production of interleukin-2 and the expression of the alpha-chain of the interleukin-2 receptor (p55), all of which appear to be correlated with the decrease in lymphocyte proliferation. Our results suggest that the culture supernatant activity might be related to interaction with monocyte-macrophage and T helper cells, especially Th1-like cells.

Adjuvants, Immunologic↗
PubMed1983

Synovial fluid lactic acid in septic and nonseptic arthritis.

We determined lactic acid levels by the lactic dehydrogenase method in synovial fluid of 41 patients with various rheumatic diseases, to test the concept that significantly elevated values were diagnostic of septic arthritis. Nine patients had septic arthritis, 15 rheumatoid arthritis (RA), and the remainder miscellaneous conditions. In another 9 patients with different rheumatic diseases, including 1 with septic arthritis, synovial fluid lactic acid was determined by both the lactic dehydrogenase and gas-liquid chromatography methods. There was a wide scatter of values among patients with septic and nonseptic inflammatory arthritis, and much overlap occurred. We could not differentiate septic arthritis from RA on the basis of synovial fluid lactic acid levels. Results were similar with both procedures for determining lactic acid levels.

Arthritis, Infectious↗
PubMed1980

Lactic acid and glucose metabolism in healthy, lactic acid-infused, and diarrheic calves.

Kinetics of glucose and lactate metabolism were measured in healthy (normal) calves, healthy calves infused with lactate, and in calves which had received an enteropathogenic coronavirus inoculum and had become diarrheic. Lactate utilization was positively correlated with blood lactate concentration in the healthy calves, but its turnover was markedly reduced in diarrheic animals. The decreased turnover was not due to inhibition of lactate oxidation, but appeared to relate to decreased gluconeogenesis. Glucose entry rate was not affected by diarrhea, but was a function of glucose concentration.

Animals↗
PubMed1997

Acceleration of post-mortem changes in Tsaiya duck (Anas platyrhynchos) breast muscle by lactic acid marination.

1. The effect of lactic acid marination at 5 degrees C on post mortem changes in breast muscle pectoralis major of spent layer Tsaiya duck was studied. 2. Myofibrils were prepared from 0.1 M and 0.2 M lactic acid marinated muscle and control (non-marinated samples) sampled at 0, 1, 3, 7 and 14 d post mortem. 3. Changes in myofibril fragmentation index (MFI), myofibrillar proteins and Z-line structure were examined. 4. Marination of duck breast muscle in lactic acid at 5 degrees C enhanced fragmentation of myofibrils and degradation of myofibrillar proteins and Z-line structure as compared to control samples. 5. In summary, lactic acid marination at 5 degrees C can accelerate the post mortem degradation of myofibrils in Tsaiya duck breast muscle.

Actinin↗
PubMed2001

Flow cytometric assessment of viability of lactic acid bacteria.

The viability of lactic acid bacteria is crucial for their applications as dairy starters and as probiotics. We investigated the usefulness of flow cytometry (FCM) for viability assessment of lactic acid bacteria. The esterase substrate carboxyfluorescein diacetate (cFDA) and the dye exclusion DNA binding probes propidium iodide (PI) and TOTO-1 were tested for live/dead discrimination using a Lactococcus, a Streptococcus, three Lactobacillus, two Leuconostoc, an Enterococcus, and a Pediococcus species. Plate count experiments were performed to validate the results of the FCM assays. The results showed that cFDA was an accurate stain for live cells; in exponential-phase cultures almost all cells were labeled, while 70 degrees C heat-killed cultures were left unstained. PI did not give clear live/dead discrimination for some of the species. TOTO-1, on the other hand, gave clear discrimination between live and dead cells. The combination of cFDA and TOTO-1 gave the best results. Well-separated subpopulations of live and dead cells could be detected with FCM. Cell sorting of the subpopulations and subsequent plating on agar medium provided direct evidence that cFDA labels the culturable subpopulation and that TOTO-1 labels the nonculturable subpopulation. Applied to cultures exposed to deconjugated bile salts or to acid, cFDA and TOTO-1 proved to be accurate indicators of culturability. Our experiments with lactic acid bacteria demonstrated that the combination of cFDA and TOTO-1 makes an excellent live/dead assay with versatile applications.

Bile Acids and Salts↗
PubMed2002

XPS and wettability characterization of modified poly(lactic acid) and poly(lactic/glycolic acid) films.

Poly(lactic acid) (PLA) and poly(lactic/glycolic acid) copolymers (PLGA) are biodegradable drug carriers of great importance, although successful pharmaceutical application requires adjustment of the surface properties of the polymeric drug delivery system to be compatible with the biological environment. For that reason, reduction of the original hydrophobicity of the PLA or PLGA surfaces was performed by applying a hydrophilic polymer poly(ethylene oxide) (PEO) with the aim to improve biocompatibility of the original polymer. PEO-containing surfaces were prepared by incorporation of block copolymeric surfactants, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (Pluronic), into the hydrophobic surface. Films of polymer blends from PLA or PLGA (with lactic/glycolic acid ratios of 75/25 and 50/50) and from Pluronics (PE6800, PE6400, and PE6100) were obtained by the solvent casting method, applying the Pluronics at different concentrations between 1 and 9.1% w/w. Wettability was measured to monitor the change in surface hydrophobicity, while X-ray photoelectron spectroscopy (XPS) was applied to determine the composition and chemical structure of the polymer surface and its change with surface modification. Substantial reduction of surface hydrophobicity was achieved on both the PLA homopolymer and the PLGA copolymers by applying the Pluronics at various concentrations. In accordance with the wettability changes the accumulation of Pluronics in the surface layer was greatly affected by the initial hydrophobicity of the polymer, namely, by the lactide content of the copolymer. The extent of surface modification was also found to be dependent on the type of blended Pluronics. Surface activity of the modifying Pluronic component was interpreted by using the solubility parameters.

Journal Article↗
PubMed1999

Probiotic spectra of lactic acid bacteria (LAB).

Lactic acid bacteria (LAB) and their probio-active cellular substances exert many beneficial effects in the gastrointestinal tract. LAB prevent adherence, establishment, and replication of several enteric mucosal pathogens through several antimicrobial mechanisms. LAB also release various enzymes into the intestinal lumen and exert potential synergistic effects on digestion and alleviate symptoms of intestinal malabsoption. Consumption of LAB fermented dairy products with LAB may elicit antitumor effects. These effects are attributed to the inhibition of mutagenic activity; decrease in several enzymes implicated in the generation of carcinogens, mutagens, or tumor-promoting agents; suppression of tumors; and the epidemiology correlating dietary regimes and cancer. Specific cellular components in LAB strains seem to induce strong adjuvant effects including modulation of cell-mediated immune responses, activation of reticuloendothelial system, augmentation of cytokine pathways and regulation of interleukins, and tumor necrosis factors. Oral administration of LAB is well tolerated and proven to be safe in 143 human clinical trials and no adverse effects were reported in any of the total 7,526 subjects studied during 1961-1998. In an effort to decrease the reliance on synthetic antimicrobials and control the emerging immunocompromised host population, the time has come to carefully explore the prophylactic and therapeutic applications of probiotic LAB.

Animals↗
PubMed2001

Surface binding of aflatoxin B(1) by lactic acid bacteria.

Specific lactic acid bacterial strains remove toxins from liquid media by physical binding. The stability of the aflatoxin B(1) complexes formed with 12 bacterial strains in both viable and nonviable (heat- or acid-treated) forms was assessed by repetitive aqueous extraction. By the fifth extraction, up to 71% of the total aflatoxin B(1) remained bound. Nonviable bacteria retained the highest amount of aflatoxin B(1). Lactobacillus rhamnosus strain GG (ATCC 53103) and L. rhamnosus strain LC-705 (DSM 7061) removed aflatoxin B(1) from solution most efficiently and were selected for further study. The accessibility of bound aflatoxin B(1) to an antibody in an indirect competitive inhibition enzyme-linked immunosorbent assay suggests that surface components of these bacteria are involved in binding. Further evidence is the recovery of around 90% of the bound aflatoxin from the bacteria by solvent extraction. Autoclaving and sonication did not release any detectable aflatoxin B(1). Variation in temperature (4 to 37 degrees C) and pH (2 to 10) did not have any significant effect on the amount of aflatoxin B(1) released. Binding of aflatoxin B(1) appears to be predominantly extracellular for viable and heat-treated bacteria. Acid treatment may permit intracellular binding. In all cases, binding is of a reversible nature, but the stability of the complexes formed depends on strain, treatment, and environmental conditions.

Aflatoxin B1↗
PubMed2002

Regulation of antimicrobial peptide production by autoinducer-mediated quorum sensing in lactic acid bacteria.

Several lactic acid bacteria produce peptides with antimicrobial activity. During the last few years, cell-cell communication has emerged as the key regulatory mechanism that controls the production of many of these antimicrobial peptides via a regulatory strategy denominated quorum sensing. Quorum sensing allows populationwide synchronised production of antimicrobial peptides as a function of cell density. The cell-cell communication phenomenon required for sensing of the cell density is mediated by secreted signalling molecules. These 'molecular messengers' accumulate in the environment as the cell density increases and activate signal transduction cascades that result in the production of antimicrobial peptides by the stimulated bacterial cell.

Bacterial Proteins↗
PubMed2002

Glutamate dehydrogenase activity: a major criterion for the selection of flavour-producing lactic acid bacteria strains.

Lactic acid bacteria (LAB) have the enzyme potential to transform amino acids into aroma compounds that contribute greatly to cheese flavour. Generally, amino acid conversion by LAB is limited by their low production of alpha-ketoglutarate since this alpha-ketoacid is essential for the first step of the conversion. Indeed, we have demonstrated that adding exogenous alpha-ketoglutarate to cheese curd, as well as using a genetically modified L. lactis strain capable of producing alpha-ketoglutarate from glutamate, greatly increased the conversion of amino acid to potent aroma compounds in cheese. Here we report the presence of glutamate dehydrogenase (GDH) activity required for the conversion of glutamate to alpha-ketoglutarate in several 'natural' LAB strains, commonly used in cheese manufacturing. Moreover, we show that the ability of LAB to produce aroma compounds from amino acids is closely related to their GDH activity. Therefore, GDH activity appears to be a major criterion for the selection of flavour-producing LAB strains, which could be used as a starter or as an adjunct to intensify flavour formation in some cheeses.

Amino Acids↗
PubMed1979

[Biological properties of antibiotic-resistant strains of lactic acid bacteria].

Lactic-acid bacteria (L. fermenti, L. acidophilus, L. delbruecki), when developing resistance to antibiotics, did not change their main biochemical, antagonistic properties and did not lose capacity for acid production. Only a decrease in their growth rate and a change in their sensitivity to the action of ultraviolet radiation were observed. Both initial and antibiotic-resistant strains were capable of taking on the mucous membrane of the large and small intestines in CBA mice.

Animals↗
PubMed1993

Chromosome mapping in lactic acid bacteria.

The chromosome structure of lactic acid bacteria has been investigated only recently. The development of pulsed-field gel electrophoresis (PFGE) combined with other DNA-based techniques enables whole-genome analysis of any bacterium, and has allowed rapid progress to be made in the knowledge of the lactic acid bacteria genome. Lactic acid bacteria possess one of the smallest eubacterial chromosomes. Depending on the species, the genome sizes range from 1.1 to 2.6 Mb. Combined physical and genetic maps of several species are already available or close to being achieved. Knowledge of the genomic structure of these organisms will serve as a basis for future genetic studies. Macrorestriction fingerprinting by PFGE is already one of the major tools for strain differentiation, identification of individual strains, and the detection of strain lineages. The genome data resulting from these studies will be of general application strain improvement.

Chromosome Mapping↗
PubMed2006

D-lactic acid production by metabolically engineered Saccharomyces cerevisiae.

Poly D-lactic acid is an important polymer because it improves the thermostability of poly L-lactic acid by the stereo complex formation. We constructed a metabolically engineered Saccharomyces cerevisiae that produces D-lactic acid efficiently. In this recombinant, the coding region of pyruvate decarboxylase 1 (PDC1) was completely deleted, and two copies of the D-lactate dehydrogenase (D-LDH) gene from Leuconostoc mesenteroides subsp. mesenteroides strain NBRC3426 were introduced into the genome. The D-lactate production reached 61.5 g/l, the amount of glucose being transformed into D-lactic acid being 61.2% under neutralizing conditions. Additionally, the yield of free D-lactic acid was also shown to be 53.0% under non-neutralizing conditions. It was confirmed that D-lactic acid of extremely high optical purity of 99.9% or higher. Our finding obtained the possibility of a new approach for pure d-lactic acid production without a neutralizing process compared with other techniques involving lactic acid bacteria and transgenic Escherichia coli.

Amino Acid Sequence↗
PubMed1981

Synovial fluid lactic acid levels in septic arthritis.

Synovial fluid lactic acid estimations were carried out on 50 samples by gas liquid chromatography. Specimens from 4 patients with bacteria arthritis, other than gonococcal, had a mean lactic acid concentration of 215 mg/dl. One patient with gonococcal arthritis had a synovial fluid lactic acid of 30 mg/dl. Forty-one patients with inflammatory arthritis and 4 patients with degenerative arthritis had mean synovial fluid lactic acid levels of 27 and 23 mg/dl respectively. The estimation of synovial fluid lactic acid is reliable in differentiating septic arthritis from inflammatory and degenerative arthritis except when the infecting organism is NEisseria gonorrhoeae.

Arthritis, Infectious↗
PubMed1997

Effect of L-lactic acid, short-chain fatty acids, and pH in cecal infusate on morphometric and cell kinetic parameters of rat cecum.

We studied the influences of cecal infusion of NaCl, short-chain fatty acids (SCFA), and L-lactic acid at pH 5.0 or 7.0 for seven days on morphometric and cell kinetic parameters of the rat cecum. SCFA increased relative weight of the mucosa and submucosa, crypt size, and mitotic index in the cecum. L-Lactic acid stimulated mitosis only at pH 5.0. Crypt size correlated positively to epithelial proliferative activity only when NaCl or L-lactic acid was infused. SCFA should have changed the balance between production and loss of the cecal epithelial cells. The infusate pH by itself had no effect, but modified the effects of SCFA and L-lactic acid in different ways. Crypt size correlated positively to the logarithm of daily proton load of infusates. The above results indicate that epithelial cell proliferation in the cecum is influenced by both SCFA and L-lactic acid, although differently, and by proton load.

Acetic Acid↗
PubMed1981

Effect and fate of orally administered lactic acid in rats.

We investigated the effect and the fate of an extremely high amount of orally administered lactic acid in rats. The dosed amount of lactic acid, 390 mg per 200 g body weight (30 times higher than that normally detected in the stomach of rats), was determined from the results of observation of acute toxicity of lactic acid in rats. Six hours after the administration of excess lactic acid together with 10 muCi of L-[U-14C]Lactic acid and 10 muCi of D-[U-14C]lactic acid, rats were sacrificed and the pH of the blood, the amount of lactic acid in each organ, L-lactate dehydrogenase (LDH) and some other enzyme activities and incorporation of radioactivities in each fraction of certain organs were measured. The control rats were given the labeled lactic acid and the same volume of water in place of cold lactic acid. Significant decrease of blood pH (delta- pH = 0.14) and increase of blood lactic acid concentration (2-fold) were observed. However, these differences were no longer observed at 24hr after the administration. The amount of lactic acid degraded to expired CO2 was 42.4% in the experimental group, whereas it was 61.3% in the control group. Radioactivities incorporated into protein and lipid fractions in the experimental group were higher than those in the control group, 3.8 and 4.9 times, respectively. It was suggested that an extremely high amount of orally administered lactic acid was utilized as an energy source, and that an excess of lactic acid was incorporated into protein and lipid in addition to degradation into CO2.

Administration, Oral↗