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PubMed2003

Production of mannitol and lactic acid by fermentation with Lactobacillus intermedius NRRL B-3693.

Lactobacillus intermedius B-3693 was selected as a good producer of mannitol from fructose after screening 72 bacterial strains. The bacterium produced mannitol, lactic acid, and acetic acid from fructose in pH-controlled batch fermentation. Typical yields of mannitol, lactic acid, and acetic acid from 250 g/L fructose were 0.70, 0.16, and 0.12 g, respectively per g of fructose. The fermentation time was greatly dependent on fructose concentration but the product yields were not dependent on fructose level. Fed-batch fermentation decreased the time of maximum mannitol production from fructose (300 g/L) from 136 to 92 h. One-third of fructose could be replaced with glucose, maltose, galactose, mannose, raffinose, or starch with glucoamylase (simultaneous saccharification and fermentation), and two-thirds of fructose could be replaced with sucrose. L. intermedius B-3693 did not co-utilize lactose, cellobiose, glycerol, or xylose with fructose. It produced lactic acid and ethanol but no acetic acid from glucose. The bacterium produced 21.3 +/- 0.6 g lactic acid, 10.5 +/- 0.3 g acetic acid, and 4.7 +/- 0.0 g ethanol per L of fermentation broth from dilute acid (15% solids, 0.5% H(2)SO(4), 121 degrees C, 1 h) pretreated enzyme (cellulase, beta-glucosidase) saccharified corn fiber hydrolyzate.

Acetic Acid↗
PubMed2002

The use of poly-L-lactic acid in lumbar interbody cages: design and biomechanical evaluation in vitro.

Cage design and cage material may play a crucial role in the incidence of postoperative complications reported with current non-absorbable interbody cage devices. Bioabsorbable poly-L-lactic acid cage devices may have potential benefits. The purpose of this study was to determine the required strength of poly-L-lactic acid cages for use in experimental goat studies and to evaluate the mechanical properties of different cage designs in situ. The yield and ultimate strength of native goat motion segments (L1-L6) were determined; the yield strength was used as a design parameter for the cages. The mechanical behaviour of two types of poly-L-lactic acid cages, the influence of endplate perforation, differences between toothed and smooth cages, and the influence of cage filling were biomechanically tested and compared to native motion segments. Only axial compression until failure of the motion segments was performed. Dual energy X-ray absorptiometry was used to determine bone mineral content. The yield and ultimate strength of the native motion segments were 3.5 and 7.0 kN, respectively. Based on these data, flexible and stiff poly-L-lactic acid cages were designed with strengths of 3.5 and 7 kN, respectively. Poly-L-lactic acid cages, whether with or without bone graft and perforating the endplates, did not reduce the compressive strength of motion segments as compared to native segments. However, toothed titanium cages, with the same geometry, negatively influenced the segments' compressive strength, which effect was reduced using smooth titanium cages.

Absorbable Implants↗
PubMed2005

Effects of nutrient supplements on simultaneous fermentation of nisin and lactic acid from cull potatoes.

The feasibility of using cull potatoes as substrate for the simultaneous production of nisin, a natural food preservative, and lactic acid, a raw material for biopolymer production, was studied. Cull potatoes are potato tubers unacceptable for food processing because of size or damage caused by bruising or disease. Although cull potatoes are enriched in various nutrients including starch, minerals, and proteins, they alone still cannot provide enough essential nutrients for the growth and metabolism of Lactococcus lactis subsp. lactis (ATCC 11454). Stimulation of bacterial growth, nisin biosynthesis, as well as lactic acid production was observed when additional nutrients such as yeast extract, peptone from meat, peptone from soy (PS), corn steep solid (CSS), and distillers' dried grains with solubles were provided. Considering the cost and availability, PS and CSS were selected as nutrient supplements for nisin and lactic acid coproduction. The conditions for nisin biosynthesis and lactic acid coproduction by L. lactis subsp. lactis in a cull potato-based medium were subsequently optimized using a statistically based experimental design.

Bioreactors↗
PubMed2001

The effect of lactic acid on odour-related host preference of yellow fever mosquitoes.

In a behavioural study we have investigated the role of lactic acid for the host preferences of yellow fever mosquitoes (Aedes aegypti) by comparing the attractiveness of rubbings from the hands of different human individuals and extracts obtained from skin rubbings from different mammals (Bos primigenius f. taurus, Capra aegagrus f. hircus, Felis silvestris f. catus and Homo sapiens). Certain human individuals were consistently more attractive to mosquitoes than others. Addition of lactic acid markedly increased the degree of attractiveness of formerly less attractive human odour samples and they were preferred over those which were originally the most attractive. There was almost no response to animal odour samples. In contrast to human samples, which contain a high amount of lactate, this compound could not be detected in samples from animals. When skin emanations from animals were combined with lactic acid, however, as many mosquitoes responded to odour samples of B. primigenius f. taurus and C. aegagrus f. hircus as did to human odours. All these data demonstrate that olfactory-based host preference of the anthropophilic mosquito A. aegypti is to a large extent due to differences in the amount of lactic acid in the odour samples.

Aedes↗
PubMedDate not supplied

Use of cerebrospinal fluid lactic acid concentration in the diagnosis of fungal meningitis.

A patient with a several year history of normal pressure hydrocephalus was found to have an infection owing to Cryptococcus neoformans. Cryptococcal infection was not suspected until typical cells were observed in a Wright's stained smear of cerebrospinal fluid (CSF). A review of past medical findings in this patient showed elevated CSF values for lactic acid and protein. This case prompted us to review the use of lactic acid as an indicator of fungal meningitis and compare it to other more commonly used nonspecific indicators of fungal meningitis, notably the concentrations of glucose and protein, and the number of leukocytes in CSF. In our institution, all 10 culturally proven cases of fungal meningitis, for which the lactic acid concentration in the CSF was available, were found to have an elevated lactic acid concentration (range 3.2 to 13.3 mmol per L vs normal range 0.8 to 2.8 mmol per L). No other nonspecific indicator was elevated in all 10 patients. In view of the poor sensitivity of stained smear or wet preparations and cultures, when less than five ml of CSF are used for culture, an elevated lactic acid value in a patient with or without signs of meningitis should raise the suspicion of fungal infection.

Blastomycosis↗
PubMed1991

Lactic acid enantiomers: separation by thin-layer chromatography on silica gel plates impregnated with Cu2+.

A simple and fast method for the separation of D- and L-lactic acid enantiomers by thin-layer chromatographic silica gel precoated plates impregnated with Cu(II) is proposed. The two lactic acid enantiomers, dissolved in acetone, are deposed on these plates. D- and L-lactic acids form complexes with Cu(II), with different Rf values, suitable for radiochemical measurements. The real separation was confirmed by enzymatic tests carried out on spots of D and L forms scraped from the chromatographic plates. Total radioactivity of 14C-labeled D- and L-lactic acids was recovered. A Cu/lactic acid complex is evidenced.

Acetone↗
PubMed1994

Use of the Escherichia coli beta-glucuronidase (gusA) gene as a reporter gene for analyzing promoters in lactic acid bacteria.

A transcriptional fusion vector, designated pNZ272, based on the promoterless beta-glucuronidase gene (gusA) of Escherichia coli as a reporter gene, has been constructed for lactic acid bacteria. The replicon of pNZ272 was derived from the Lactococcus lactis plasmid pSH71, allowing replication in a wide range of gram-positive bacteria and E. coli. The applicability of pNZ272 and the expression of the gusA gene in L. lactis was demonstrated in shotgun cloning experiments with lactococcal chromosomal and bacteriophage DNA. In addition, three defined lactococcal promoters were inserted in pNZ272: the plasmid-derived lacA promoter, the chromosomal usp45 promoter, and a promoter from bacteriophage phi SK11G. The three resulting plasmids showed beta-glucuronidase activity in a gusA-deficient E. coli strain and in four species of lactic acid bacteria belonging to the genera Lactobacillus, Lactococcus, and Leuconostoc. The copy numbers of the gusA-expressing plasmids were similar within a single species of lactic acid bacteria. However, the specific beta-glucuronidase activity and the gusA mRNA levels varied considerably both within a single species and among different species of lactic acid bacteria. The transcriptional start site of all three promoters was determined and found to be identical in the different species. The results of this comparative promoter analysis indicate that the requirements for efficient transcription initiation differ among the lactic acid bacteria studied.

Amino Acid Sequence↗
PubMed1995

Influences on the gamma-muscle-spindle system from contralateral muscle afferents stimulated by KCl and lactic acid.

The aim of the present study was to investigate whether increased concentrations of lactic acid and potassium chloride (KCl) in contralateral muscles can influence the sensitivity of primary and secondary muscle spindle afferents (MSAs) from ipsilateral extensor and flexor muscles. The experiments were performed on 7 cats anaesthetised with alpha-chloralose. Recordings were made simultaneously from 2-12 single MSAs from the triceps surae (GS) and/or the posterior biceps and semitendinosus muscles (PBSt). The mean rate of firing and the amplitude of a fitted sine curve of MSA responses to sinusoidal stretching of the receptor bearing muscles were determined. Responses of 42 primary MSAs (17 from PBSt and 25 from GS) were recorded. On 33 of these, clear-cut alterations in sinusoidal response were evoked by injection of 1 ml KCl (200-400 mM) or 1 ml lactic acid (20-50 mM) into the arterial supply of the contralateral GS or PBSt muscles. Six out of 8 secondary MSAs showed sizeable effects to increased intramuscular concentrations of KCl and/or lactic acid (3 from PBSt and 3 from GS). On both primary and secondary MSAs, from GS as well as from PBSt muscles, the large majority of effects were excitatory. All effects on secondary MSAs were compatible with reflex actions on static fusimotor neurones, whereas on primary MSAs different types of reflex responses were observed (i.e. pure static, pure dynamic and mixtures of static and dynamic fusimotor actions). Stimuli related alterations in MSA responses were completely abolished when the contralateral GS or PBSt nerves were anaesthetised.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1976

[Possible participation of lactic acid in formation of a non-mediator agent stimulating the heart during exposure of the myocardium to sympathetic influences].

Release of A-factor, the physiologically active substance of a non--mediatory nature under sympathetic stimulation, depends upon the glycolytic process. To examine the assumption that A-factor may be a glycolytic product, lactic acid was studied in particular, and it was shown that A-factor is not identical to lactic acid. However it was found out that lactic acid participates in the release of A-factor in the heart. It was shown that under the effect of lactic acid a substance having high cardiostimulating activity was released in the frog heart muscle. This cardiostimulating substance as well as A-factor increases the amplitude of contractions of A-factor, was not abolished with beta-sympathicolytic inderal. The ability of both substances to stimulate heart activity was preserved after 20 min heating in a water bath. The cardiostimulating substance similar to A-factor increases heart sensitivity to sympathetic and decreases it to parasympathetic stimulations. It may be suggested that the cardiostimulating substance released in the heart under the effect of lactic acid is identical to A-factor released in the myocardium under the action of catecholamines and stimulation of the sympathetic nerve.

Acetylcholine↗
PubMed2005

Efficient production of L-Lactic acid by metabolically engineered Saccharomyces cerevisiae with a genome-integrated L-lactate dehydrogenase gene.

We developed a metabolically engineered yeast which produces lactic acid efficiently. In this recombinant strain, the coding region for pyruvate decarboxylase 1 (PDC1) on chromosome XII is substituted for that of the l-lactate dehydrogenase gene (LDH) through homologous recombination. The expression of mRNA for the genome-integrated LDH is regulated under the control of the native PDC1 promoter, while PDC1 is completely disrupted. Using this method, we constructed a diploid yeast transformant, with each haploid genome having a single insertion of bovine LDH. Yeast cells expressing LDH were observed to convert glucose to both lactate (55.6 g/liter) and ethanol (16.9 g/liter), with up to 62.2% of the glucose being transformed into lactic acid under neutralizing conditions. This transgenic strain, which expresses bovine LDH under the control of the PDC1 promoter, also showed high lactic acid production (50.2 g/liter) under nonneutralizing conditions. The differences in lactic acid production were compared among four different recombinants expressing a heterologous LDH gene (i.e., either the bovine LDH gene or the Bifidobacterium longum LDH gene): two transgenic strains with 2microm plasmid-based vectors and two genome-integrated strains.

Animals↗
PubMed1999

[Prolonged antinociceptive effect of poly (DL-lactic acid)-fentanyl composites after their intrathecal injection in rats].

We synthesized poly (DL-lactic acid)-fentanyl composites and compared the duration of analgesia after the administration of a single intrathecal dose of these agents in rats. The drug was injected with an intrathecal catheter into the intrathecal space. Fentanyl composites or plain fentanyl in doses of 2.5 or 25 micrograms were administered, respectively. Animals were then tested for analgesia using the tail-flick test. The release rate of fentanyl from fentanyl composites in vitro was also evaluated. The antinociceptive effect of fentanyl composites (25 micrograms) was significantly longer than that of plain fentanyl. Administration of poly (DL-lactic acid) alone did not induce the antinociceptive effect. Four of 7 animals given plain fentanyl (25 micrograms) exhibited temporary respiratory depression, but none of the animals given fentanyl composites showed this response. In vitro experiments demonstrated a slow release of fentanyl from the fentanyl composites. We conclude that the antinociceptive effect of fentanyl can be prolonged when administered as a poly (DL-lactic acid)-fentanyl composite in the intrathecal space with decreased systemic side effects compared with the plain formulation.

Analgesics, Opioid↗
PubMed2005

Preparation of gelatin microspheres containing lactic acid--effect of cross-linking on drug release.

In this study, gelatin microspheres containing lactic acid were prepared by the polymerization technique using glutaraldehyde as the cross-linking agent. Dried microspheres were loaded by immersing them in an aqueous solution of lactic acid. In order to prepare microspheres with an appropriate drug release profile, the effect of time of cross-linking and the amount of cross-linking agent on the swelling properties of microspheres and their release profile were investigated. The microencapsulation efficiency, microspheres appearance, particle size, swelling ratio and drug release profile were also studied. Microspheres prepared with a larger amount of cross-linking agent, or after longer cross-linking time, showed a reduced swelling ratio in aqueous media. In vitro release pattern of lactic acid from gelatin microspheres showed a biphasic profile and the release rates were reduced upon increasing the amount of cross-liking agent and prolonging the cross-linking time.

Aging↗
PubMed1982

Elevation of the blood lactate concentration by alkali therapy without requiring additional lactic acid accumulation: theoretical considerations.

A patient presented with lactic acidosis and severe acidemia; sodium bicarbonate was administered to titrate the very large hydrogen ion load. Coincident with this therapy, the blood lactate concentration rose from 21 to 27 mmole/L. In order to evaluate whether this rise in lactate could have occurred without requiring additional net lactic acid production, the effect of the hydrogen ion concentration on lactate distribution was evaluated. Data obtained from animal studies support the established hypothesis that lactate is distributed like other weak organic acids at steady-state; hence, alkalemia should favor a shift of lactate from the intracellular fluid (ICF) to the extracellular fluid (ECF). The authors calculated that the blood lactate concentration could rise by 50% without requiring net lactic acid accumulation when the severe acidemia was corrected by alkali therapy. Thus, an increase in lactate concentration of the magnitude observed during alkali therapy need not indicate a worsening of the metabolic picture in lactic acidosis.

Alkalies↗
PubMed2000

Measurement of the concentrations of glucose and lactic acid in peritoneal dialysis solutions using near-infrared spectroscopy.

Near-infrared spectroscopy (NIR), a nondestructive analytical technique, was employed for the simultaneous determination of the concentrations of glucose and lactic acid in peritoneal dialysis solutions. Solutions were placed in a near-infrared spectrophotometer and the absorbance at wavelengths between 400 and 2500 nm was measured at 2 nm intervals. To obtain calibration equations, multiple linear regression (MLR) was carried out on the NIR spectral data and on the glucose and lactic acid concentrations obtained by enzymatic methods using a calibration sample set. The value of the simple correlation coefficient (r) was 0.996 when using a wavelength of 2270 nm for glucose. The value of the multiple correlation coefficient (R) for lactic acid was 0.997 when using wavelengths of 1688 and 1268 nm. To validate the calibration equations obtained, glucose and lactic acid concentrations in a prediction sample set which was not used for calibration were calculated using the calibration equation and compared with the concentrations measured by the enzymatic method. Excellent agreement between the results of the enzymatic method and of NIR was observed for both constituents. Concentrations of glucose and lactic acid in the peritoneal dialysis solutions were analyzed simultaneously by NIR. The procedure for NIR was simple, and the operation time required to determine the concentrations was a few minutes. These results indicate that NIR may be a useful method for monitoring of the production of peritoneal dialysis solutions.

Journal Article↗
PubMed2006

Lactic acid and exercise performance : culprit or friend?

This article critically discusses whether accumulation of lactic acid, or in reality lactate and/or hydrogen (H+) ions, is a major cause of skeletal muscle fatigue, i.e. decline of muscle force or power output leading to impaired exercise performance. There exists a long history of studies on the effects of increased lactate/H+ concentrations in muscle or plasma on contractile performance of skeletal muscle. Evidence suggesting that lactate/H+ is a culprit has been based on correlation-type studies, which reveal close temporal relationships between intramuscular lactate or H+ accumulation and the decline of force during fatiguing stimulation in frog, rodent or human muscle. In addition, an induced acidosis can impair muscle contractility in non-fatigued humans or in isolated muscle preparations, and several mechanisms to explain such effects have been provided. However, a number of recent high-profile papers have seriously challenged the 'lactic acid hypothesis'. In the 1990s, these findings mainly involved diminished negative effects of an induced acidosis in skinned or intact muscle fibres, at higher more physiological experimental temperatures. In the early 2000s, it was conclusively shown that lactate has little detrimental effect on mechanically skinned fibres activated by artificial stimulation. Perhaps more remarkably, there are now several reports of protective effects of lactate exposure or induced acidosis on potassium-depressed muscle contractions in isolated rodent muscles. In addition, sodium-lactate exposure can attenuate severe fatigue in rat muscle stimulated in situ, and sodium lactate ingestion can increase time to exhaustion during sprinting in humans. Taken together, these latest findings have led to the idea that lactate/H+ is ergogenic during exercise. It should not be taken as fact that lactic acid is the deviant that impairs exercise performance. Experiments on isolated muscle suggest that acidosis has little detrimental effect or may even improve muscle performance during high-intensity exercise. In contrast, induced acidosis can exacerbate fatigue during whole-body dynamic exercise and alkalosis can improve exercise performance in events lasting 1-10 minutes. To reconcile the findings from isolated muscle fibres through to whole-body exercise, it is hypothesised that a severe plasma acidosis in humans might impair exercise performance by causing a reduced CNS drive to muscle.

Acidosis, Lactic↗
PubMed1998

Comparison of water wash, trimming, and combined hot water and lactic acid treatments for reducing bacteria of fecal origin on beef carcasses.

Cleaning treatments, such as high-pressure water wash at 35 degrees C or trim, alone and combined with sanitizing treatments, such as hot water (95 degrees C at the source), warm (55 degrees C) 2% lactic acid spray, and combinations of these two sanitizing methods, were compared for their effectiveness in reducing inoculated numbers (5.0 to 6.0 log CFU/cm2) of Salmonella typhimurium, Escherichia coli O157:H7, aerobic plate counts, Enterobacteriaceae, total coliforms, thermotolerant coliforms, and generic E. coli on hot beef carcass surface areas in a model carcass spray cabinet. Log reductions in numbers of all tested organisms by water wash or trim alone were significantly smaller than the log reductions obtained by the different combined treatments. Regardless of the cleaning treatment (water wash or trim) or surface area, the range for mean log reductions by hot water was from 4.0 to > 4.8 log CFU/cm2, by lactic acid spray was from 4.6 to > 4.9 log CFU/cm2, by hot water followed by lactic acid spray was from 4.5 to > 4.9 log CFU/cm2, and by lactic acid spray followed by hot water was from 4.4 to > 4.6 log CFU/cm2, for S. typhimurium and E. coli O157:H7. Identical reductions were obtained for thermotolerant coliforms and generic E. coli. No differences in bacterial reductions were observed for different carcass surface regions. Water wash and trim treatments caused spreading of the contamination to other areas of the carcass surface while providing an overall reduction in fecal or pathogenic contamination on carcass surface areas. This relocated contamination after either water wash or trim was most effectively reduced by following with hot water and then lactic acid spray. This combined treatment yielded 0% positive samples for S. typhimurium, E. coli O157:H7, thermotolerant coliforms, and generic E. coli on areas outside the inoculated areas, whereas percent positive samples after applying other combined treatments ranged from 22 to 44% for S. typhimurium, 0 to 44% for E. coli O157:H7, and 11 to 33% for both thermotolerant coliforms and generic E. coli. From data collected in this study, it is possible to choose an effective, inexpensive treatment to reduce bacterial contamination on beef carcasses. In addition, the similar reduction rates of total coliforms, thermotolerant coliforms, or generic E. coli may be useful in identifying an indicator to verify the effectiveness of the selected treatment as a critical control point in a Hazard Analysis and Critical Control Point program.

Animals↗
PubMedDate not supplied

Poly-L-lactic acid: a new dimension in soft tissue augmentation.

Poly-L-lactic acid (PLLA) is a biodegradable, synthetic polymer of L-lactic acid that has been used in a variety of human medical applications for over 40 years. It has recently been approved in the United States for the treatment of HIV-associated facial lipoatrophy. This indication, combined with a European experience that indicates a clinical benefit persisting for up to 2 years, has made PLLA an increasingly popular injectable soft tissue filler in healthy patients. However, controlled clinical studies are necessary to determine whether PLLA benefits healthy patients seeking contour restoration as much as patients seeking treatment for HIV facial lipoatrophy. The present authors reviewed the background and clinical applications of PLLA as treatment for HIV-associated facial lipoatrophy and age-related facial volume loss.

Absorbable Implants↗