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PubMed1992

Hyperglycemia and the rate of lactic acid accumulation during cerebral ischemia in developing animals: in vivo proton MRS study.

During cerebral ischemia, hyperglycemia has a deleterious effect upon the adult brain but not the neonatal brain. This phenomenon may be related to the fact that hyperglycemia in adult animals subjected to cerebral ischemia raises the ischemic accumulation of lactate by as much as 10-fold. The purpose of this study was to determine whether hyperglycemia during cerebral ischemia produces a similar increase in the rate of lactic acid accumulation in developing animals. Data from in vivo proton magnetic resonance spectroscopic experiments showed that blood glucose concentration did not affect the rate of lactic acid accumulation during cerebral ischemia in either the neonatal dog or juvenile rabbit. The lack of increase in the ischemic rate of lactic acid accumulation during hyperglycemia in the developing animal contrasts sharply with the marked effect of blood glucose concentration upon the rate of lactic acid accumulation in the adult animal. Differences in the total amount of lactic acid formed and the rate at which it is accumulated may contribute, in part, to the greater tolerance of the young animal to cerebral ischemia.

Aging↗
PubMed2005

Effects of aeration on growth and on production of bacteriocins and other metabolites in cultures of eight strains of lactic acid bacteria.

In general, it is accepted that the production of bacteriocins in lactic acid bacteria cultures implies moderately to highly restrictive conditions regarding the availability of oxygen. However, the situation appears to be more complex, probably owing to the facultative anaerobic character of these microorganisms. By studying the culture of eight strains of lactic acid bacteria carried out in vessels with different loads of medium within an interval that determines linearly the minimum availability of oxygen, the existence of three types of behavior was highlighted: production increases (1) with the availability of oxygen, (2) with the restriction of this availability, and (3) toward both extremes of these conditions, diminishing in intermediate situations. These behaviors affected not only the production of bacteriocins, but also their metabolic character (in the Luedeking and Piret sense), as well as the production of other characteristic metabolites, such as lactic acid, acetic acid, and ethanol.

Bacteriocins↗
PubMed2001

Operating conditions that affect the resistance of lactic acid bacteria to freezing and frozen storage.

Thermophilic lactic acid bacteria exhibit different survival rates during freezing and frozen storage, depending on the processing conditions. We used a Plackett and Burman experimental design to study the effects of 13 experimental factors, at two levels, on the resistance of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus to freezing and frozen storage. The resistance was evaluated by quantifying the decrease of acidification activity during freezing and throughout 8 weeks of storage. Acidification activity after freezing and frozen storage was affected by 12 experimental factors. Only the thawing temperature did not show any significant effect. S. thermophilus was more resistant than L. bulgaricus and the cryoprotective effect of glycerol during freezing and storage was confirmed. The temperature and duration of the cryoprotection step influenced acidification activity following the freezing step: the lower the temperature and the shorter the duration, the higher the activity. Acidification activity after storage was affected by several experimental factors involved in the fermentation stage: use of NaOH instead of NH4OH for pH control, addition of Tween 80 in the culture medium, and faster cooling led to better cryotolerance. Resistance to freezing and frozen storage was improved by using a high freezing rate and a low storage temperature. Finally, this study revealed that the conditions under which lactic acid bacteria are prepared should be well controlled to improve their preservation and to limit the variability between batches and between species.

Cryopreservation↗
PubMed1995

Lactic acid decontamination of fresh pork carcasses: a pilot plant study.

Lactic acid decontamination (LAD) was carried out in an abattoir on pork carcasses, artificially contaminated with Salmonella typhimurium in faeces suspensions. The surface contamination with S. typhimurium ranged from 1-2 log10 cfu/cm2. Before cold and hot LAD was undertaken, the inoculum was allowed to adhere to the meat surface for 20 min. Cold LAD consisted of treatment for 60 s with 2% (pH 2.3) or 5% (pH 1.9) lactic acid (LA); for hot LAD the exposure times were 30, 60, 90 and 120 s. The spray nozzle temperatures were 11 degrees C and 55 degrees C, and that of the treated meat surface 16-18 degrees C and 36-38 degrees C, respectively. Treatment with cold 2% and 5% LA for 60 s eliminated S. typhimurium from pork carcasses inoculated with ca. 1 log10 cfu/cm2, but not from those inoculated at ca. 2 log10 cfu/cm2. However, this could be achieved by hot 2% and 5% LA sprayed for 60-120 s. Also exposures of at least 30 s using these hot LA solutions eliminated S. typhimurium consistently from carcasses inoculated with ca. 1 log10 cfu/cm2. Rinsing-off contributed only marginally to contamination reduction. Application of 2% or 5% LA for 120 s led to an unacceptable deterioration of the organoleptic qualities of the meat. Addition of nicotinic and ascorbic acid as colour stabilizers to the spraying solutions reduced these changes to just acceptable levels when 2% LA was used.

Abattoirs↗
PubMed2006

Production of lactic acid and fructose from media with cane sugar using mutant of Lactobacillus delbrueckii NCIM 2365.

AIMS: To examine the potential of Lactobacillus delbrueckii mutant, Uc-3 to produce lactic acid and fructose from sucrose-based media. METHODS AND RESULTS: The mutant of L. delbrueckii NCIM 2365 was cultivated in shake flask containing hydrolysed cane sugar (sucrose)-based medium. The lactic acid yield and volumetric productivity with hydrolysed cane concentration up to 200 g l(-1) were in the range of 92-97% of the theoretical value and between 2.7 and 3.8 g l(-1) h(-1), respectively. The fructose fraction of the syrup produced was more than 95% when the total initial sugar concentration in the medium was higher (150-200 g l(-1)). There are no unwanted byproducts detected in the fermentation broth. CONCLUSIONS: We demonstrated that L. delbrueckii mutant Uc-3 was able to utilize glucose preferentially to produce lactic acid and fructose from hydrolysed cane sugar in batch fermentation process. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings will be useful in the production of lactic acid and high fructose syrups using media with high concentrations of sucrose-based raw materials. This approach can lead to modification of the traditional fermentation processes to obtain value-added byproducts, attaining better process economics.

Biotechnology↗
PubMed1996

Hydrolytic degradation of the coral/poly(DL-lactic acid) bioresorbable material.

A bioresorbable composite material composed of a high molecular weight poly(DL-lactic acid) and granules of natural coral (40/60 w/w) was made by blending in acetone with further evaporation of the solvent. The blend and the unfilled polymer matrix were compression moulded and machined to yield 12 x 12 mm plates of different thicknesses (1.4 mm for the blend vs 2.1 mm for the polymer). The resulting plates were allowed to age at 37 degrees C in a pH 7.4 isoosmolar phosphate buffer solution taken as a model of body fluids. Hydrolytic degradation of the blend was investigated comparatively with the unfilled polymer matrix. The fate of the specimens was monitored by weighing, enzymatic assay, size-exclusion chromatolography and differential scanning calorimetry. Data on water absorption, weight loss, release of L-lactic acid, molecular weight and morphology changes conclusively showed that the presence of coral dramatically modified the degradation characteristics of poly(DL-lactic acid). In particular, the faster internal degradation observed for the unfilled polymer matrix was not detected for the blend. This finding was assigned to the buffering effect of calcium carbonate which neutralized the carboxyl end groups of the degradation products and to the presence of coral/polymer interfaces which facilitated ion exchanges with the external solution, both contributing to eliminate autocatalysis.

Animals↗
PubMed1996

Hydrolytic degradation of films prepared from blends of high and low molecular weight poly(DL-lactic acid)s.

Biodegradable films were prepared by casting acetone solutions of mixtures of a high molecular weight poly(DL-lactic acid) (HMW-PLA50) with 0, 10, and 30% w/w poly(DL-lactic acid) oligomers (LMW-PLA50), before drying. From size exclusion chromatography (SEC) it was shown that degradation occurred during film processing, in agreement with the acid-catalyzed degradation of polyesters. The higher the content of LMW-PLA50, the larger the decrease of the molar masses. The three selected film formulations were then allowed to age in isoosmolar 0.13M, pH 7.4 sodium phosphate buffer at 37 degrees C. The hydrolytic degradation was monitored by using various techniques, namely weighing to quantify water absorption and weight loss, SEC to evaluate molar mass changes, head space gas chromatography to assess the desorption of residual acetone, and enzymatic assay of the L-lactic acid released in the aging media. The presence of LMW-PLA50 clearly accelerated film degradation. Moreover, it was shown that the mechanism of degradation greatly depended on the content in the oligomers.

Absorption↗
PubMed1987

Lactic acid concentration and acid-base balance in cerebrospinal fluid: observations of diagnostic importance in non-Hodgkin lymphoma.

Measurements of lactic acid concentration and gas analysis were performed in lumbar cerebrospinal fluid from 36 patients without malignant central nervous system involvement and four patients with meningeal dissemination of non-Hodgkin lymphoma. The upper lactic acid concentration in controls of 2.48 mmol/l was exceeded in all four patients, also in cases with low blast counts and normal protein and glucose content. The pH, pCO2, pO2 and standard bicarbonate concentration in spinal fluid of patients with meningeal dissemination in non-Hodgkin lymphoma did not show significant differences compared with other patients and controls. Determination of the lactic acid concentration in cerebrospinal fluid add information, relevant to the diagnosis of meningeal involvement in non-Hodgkin lymphoma.

Acid-Base Equilibrium↗
PubMed2007

Fermentative production of lactic acid from biomass: an overview on process developments and future perspectives.

The concept of utilizing excess biomass or wastes from agricultural and agro-industrial residues to produce energy, feeds or foods, and other useful products is not necessarily new. Recently, fermentation of biomass has gained considerable attention due to the forthcoming scarcity of fossil fuels and also due to the necessity of increasing world food and feed supplies. A cost-effective viable process for lactic acid production has to be developed for which several attempts have been initiated. Fermentation techniques result in the production of either D: (-) or L: (+) lactic acid, or a racemic mixture of both, depending on the type of organism used. The interest in the fermentative production of lactic acid has increased due to the prospects of environmental friendliness and of using renewable resources instead of petrochemicals. Amylolytic bacteria Lactobacillus amylovorus ATCC 33622 is reported to have the efficiency of full conversion of liquefied cornstarch to lactic acid with a productivity of 20 g l(-1) h(-1). A maximum of 35 g l(-1) h(-1) was reported using a high cell density of L. helveticus (27 g l(-1)) with a complete conversion of 55- to 60-g l(-1) lactose present in whey. Simultaneous saccharification and fermentation is proved to be best in the sense of high substrate concentration in lower reactor volume and low fermentation cost. In this review, a survey has been made to see how effectively the fermentation technology explored and exploited the cheaply available source materials for value addition with special emphasis on lactic acid production.

Biomass↗
PubMed1984

Effect of intermittent infusions of glucose-containing crystalloid cardioplegic solution on myocardial tissue lactic acid and recovery of contractility.

The objective of this study was to determine the effects of single or intermittent infusions of cardioplegic solution with glucose (5 gm/L) or without glucose on myocardial tissue lactic acid and recovery of myocardial contractility following 80 minutes of total ischemia at 28 degrees C in the isolated, blood-perfused, beating rabbit heart. Ischemia without cardioplegia increased tissue lactic acid (6.79 mg/gm tissue) above the control value (0.9 mg/gm tissue), p less than 0.0025). Lactic acid following single infusions with (4.19 mg/gm tissue) or without glucose (3.67 mg/gm tissue) was significantly greater (p less than 0.0025) than tissue lactic acid following intermittent infusions with (1.06 mg/gm tissue) or without glucose (1.05 mg/gm tissue). Cardioplegic arrest in all cases significantly decreased tissue lactate accumulation when compared to arrest without cardioplegia (p less than 0.01). The decrease in myocardial contractility demonstrated when no cardioplegic protection was employed (86% recovery) was completely eliminated (100% recovery) with a single-bolus infusion of cardioplegic solution containing glucose (p less 0.025). Intermittent infusions of cardioplegic solution containing glucose (92% recovery) and single infusions without glucose (93% recovery) also improved recovery of contractility following ischemia, but the results were not statistically significant.

Animals↗
PubMed1985

Effects of dopamine and dobutamine on hemodynamics and plasma catecholamine levels during severe lactic acid acidosis.

This study was designed to evaluate the effects of dopamine and dobutamine on hemodynamics and plasma catecholamine levels during experimental lactic acid acidosis in dogs. During the normal acid-base state (pH 7.4, PCO2 40 mm Hg), cardiac output and stroke volume were significantly increased and systemic vascular resistance was decreased by the infusion of dopamine or dobutamine 20 mcg/kg/min. Dobutamine produced identical changes in cardiac output, stroke volume, and systemic vascular resistance even during severe lactic acid acidosis (pH 7.0, PCO2 40 mm Hg). Dopamine, however, failed to increase cardiac output and stroke volume and to decrease systemic vascular resistance during lactic acidosis. The plasma norepinephrine level was elevated from 0.49 to 3.01 ng/ml during normal acid-based state and from 1.76 to 9.53 ng/ml during severe lactic acid acidosis by the infusion of dopamine. Dobutamine infusion did not affect the plasma norepinephrine level during normal acid-base state but reduced the level during lactic acid acidosis. The marked increase in plasma norepinephrine following dopamine infusion may explain both the decrease in cardiac output and the increase in systemic vascular resistance in response to dopamine infusion during severe lactic acid acidosis. These results indicate that dobutamine may be more useful than dopamine in improving cardiac output during severe acidosis.

Acid-Base Equilibrium↗
PubMed2006

The effect of pyruvate decarboxylase gene knockout in Saccharomyces cerevisiae on L-lactic acid production.

A plant- and crop-based renewable plastic, poly-lactic acid (PLA), is receiving attention as a new material for a sustainable society in place of petroleum-based plastics. We constructed a metabolically engineered Saccharomyces cerevisiae that has both pyruvate decarboxylase genes (PDC1 and PDC5) disrupted in the genetic background to express two copies of the bovine L-lactate dehydrogenase (LDH) gene. With this recombinant, the yield of lactate was 82.3 g/liter, up to 81.5% of the glucose being transformed into lactic acid on neutralizing cultivation, although pdc1 pdc5 double disruption led to ineffective decreases in cell growth and fermentation speed. This strain showed lactate productivity improvement as much as 1.5 times higher than the previous strain. This production yield is the highest value for a lactic acid-producing yeast yet reported.

Bioreactors↗
PubMed1995

Lactic acid production from molasses by Sporolactobacillus cellulosolvens.

Sporolactobacillus cellulosolvens (NCIMB 12173) isolated from an anaerobic digester and characterised biochemically is being reported for homofermentative lactic acid production from molasses in a batch culture. The effect of various process parameters on lactic acid production were optimized. A maximum lactic acid (24.2 g/l) and yield coefficient (0.79) was achieved using 3% (v/v) inoculum of 36 h old culture in molasses medium containing sugars (5%; w/v) supplemented with peptone (2.5 g/l) and (NH4)2SO4 (7.5 g/l), pH 6.5 at 40 degrees C after 72 h of fermentation.

Bacillaceae↗
PubMed2006

Transparent micro- and nanopatterned poly(lactic acid) for biomedical applications.

The formation of structures in poly(lactic acid) has been investigated with respect to producing areas of regular, superficial features with dimensions comparable to those of cells or biological macromolecules. Nanoembossing, a novel method of pattern replication in polymers, has been used for the production of features ranging from tens of micrometers, covering areas up to 1 cm(2), down to hundreds of nanometers. Both micro- and nanostructures are faithfully replicated. Contact-angle measurements suggest that positive microstructuring of the polymer (where features protrude from the polymer surface) produces a more hydrophilic surface than negative microstructuring. The ability to structure the surface of the poly(lactic acid), allied to the polymer's postprocessing transparency and proven biocompatibility, means that thin films produced in this way will be useful for bioengineers studying the interaction of micro- and nanodimensioned features with biological specimen, with regard to tissue engineering, for example.

Biocompatible Materials↗
PubMed2000

Production of lactic acid from pulp mill solid waste and xylose using Lactobacillus delbrueckii (NRRL B445).

Using the simultaneous saccharification and fermentation (SSF) technique, pulp mill solid waste cellulose was converted into glucose using cellulase enzyme and glucose into lactic acid using NRRL B445. SSF experiments were conducted at various pH levels, temperatures, and nutrient concentrations, and the lactic acid yield ranged from 86 to 97%. The depletion of xylose in SSF was further investigated by inoculating NRRL B445 into a xylose-only medium. On prolonged incubation, depletion of xylose with lactic acid production was observed. An experimental procedure with a nonglucose medium was developed to eliminate the lag phase. From xylose fermentation, Lactobacillus delbrueckii yielded 88-92% lactic acid and 2-12% acetic acid.

Cellulase↗
PubMed1995

Effects of potassium and lactic acid on chemoreceptor discharge in anaesthetized cats.

Both increasing [K+]a and falling pHa stimulate ventilation through an action on the peripheral chemoreceptors. We have examined the effect on afferent carotid chemoreceptor discharge, of intravenous infusion of lactic acid alone, KCl alone, and both combined at constant PETCO2 in anaesthetized, artificially ventilated cats. Infusions of lactic acid alone and KCl alone caused similar increases in both the mean and amplitude of oscillation of chemoreceptor discharge. In the case of the lactic acid alone infusion the increase in the amplitude of oscillation could be accounted for by the resultant increase in carbon dioxide production. Simultaneous infusion of KCl and lactic acid caused an increase in the mean and amplitude of the discharge which was greater than either given alone, although the combined effect was less than additive. The alterations in mean and amplitude of oscillation of discharge during infusion of both agents together may be completely accounted for by a combined effect of increased carbon dioxide production and elevated [K+]a.

Anesthesia↗
PubMed1998

The ecotoxicity and the biodegradability of lactic acid, alkyl lactate esters and lactate salts.

The ecotoxicity of lactic acid, its alkyl esters and selected metal salts was studied experimentally with the micro alga Selenastrum capricornutum, the crustacean Daphnia magna and the fish species Brachydanio rerio and Pimephales promelas. In addition, the biodegradation of lactate esters was also studied. The aim of the study was to provide predicted environmental data for additional alkyl homologues and metal salts. The ecotoxicity data are evaluated by means of Structure Activity Relations (SAR), using literature data on a non-polar narcotic mechanism of toxicity as a baseline for comparison. Lactate salts were evaluated by comparison to the toxicity of the metal ion. For the fish and D. magna, it was evident that methyl, ethyl, propyl and to a lesser extent butyl lactate were slightly more toxic in comparison to baseline non-polar narcotic toxicity data. The toxicity tests carried out with lactate-salts demonstrated clearly that the toxicity in standard tests is only determined by the associated cation and not by the lactate part. Lactic acid and its alkyl esters were degraded for more than 60% in the ready biodegradability tests and from the data presented, it is evident that the majority of alkyl lactates are readily biodegradable. The results presented in this study indicate that alkyl lactate esters show some differences in their ecotoxicity when compared to non polar narcotic compounds in but that these differences are generally small. When aquatic toxicity is considered together with their rapid tendency to biodegrade, it is concluded that lactate esters show generally favourable environmental characteristics.

Animals↗
PubMed2005

Satisfaction and tolerability of combination of lactoserum and lactic acid on the external genitalia in Thai women.

OBJECTIVE: The aims of this study were to assess the user satisfaction and tolerability of a combination of lactoserum and lactic acid on the external genitalia of Thai women. MATERIAL AND METHOD: Women who were over 18 years of age who came to gynecologic outpatient unit at Rajavithi Hospital from November 2004 to January 2005, without clinical manifestations of vulvovaginal irritation or infection were included. The exclusion criteria were women who had allergy to a combination of lactoserum and lactic acid, or any of the components of this product. Clinical history was taken and gynaecological examination was performed. Those who met the eligible criteria were assigned to use one bottle of 150 ml combination of lactoserum and lactic acid on the external genitalia. Fisher's Exact test was used to compare the satisfaction between each group. RESULTS: There were 300 patients equally dividing in 3 groups. Average age was 42.2 +/- 9.8 years. The satisfaction percentage was more than 90 percent according to the evaluation criteria. There was no statistically significant difference between products. The tolerability were high percentage, only 3.3% of the patients used these products less than 7 days. 6 patients (2%) experienced discomfort resulting from these products and no statistically significant difference between products. CONCLUSION: The combination of lactoserum and lactic acid demonstrated the high percentage of satisfaction and tolerability. Only 2% of patients experienced discomfort without any serious discomfort effects.

Adult↗