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PubMed2006

Subdermal implants of poly(L-lactic acid) with plasticizer: an ultrastructural study in rats.

Poly(L-lactic acid) (PLLA) membranes containing 7% triethylcitrate plasticizer were implanted in the subcutaneous tissue of rats, and the cellular reaction was evaluated over a period of 2-180 days. The samples were processed for conventional transmission electron microscopy. Polymorphonuclear-type cells and a fibrin network were seen within membrane pores 2 days after implantation. In subsequent samples, there was cellular infiltration, which consisted mainly of fibroblasts, macrophages and multinuclear giant cells embedded in an abundant extracellular matrix containing a network of collagen fibers and blood vessels. At 90 and 180 days after implantation, a high density of voluminous phagocytic cells with a large number of endocytic polymer fragments within their cytoplasm was seen. These results show that PLLA membranes can support connective tissue proliferation and remodeling, which are important properties for successful bio-protheses.

Animals↗
PubMed1991

Vascular lactic acid infusions do not alter the incidence of fetal breathing movements or their inhibition by acute hypoxemia.

Hypoxemia transiently inhibits the incidence of fetal breathing movements (FBM), but their incidence returns to normal after several hours despite maintained hypoxemia. We hypothesized that the lactic acidosis associated with prolonged systemic hypoxemia might mediate the adaptation of the hypoxemic inhibition of FBM. In sheep fetuses, the incidence of FBM was measured in a control hour and during 6 h of i.v. infusion of L-lactic acid, which raised the blood lactate concentrations to levels seen with moderate hypoxemia. FBM were observed at the same incidence as during control during each of the first 4 h (all approximately 40%). In the 5th h of lactic acid infusion, fetal hypoxemia was induced by lowering maternal inspired oxygen fraction and FBM occurred only 8 +/- 1% (SEM) of that hour. In a subsequent normoxemic recovery hour, the incidence of FBM remained below control levels. In the same animals on a different day, a similar hypoxemia induced without the acid infusion caused a comparable inhibition of FBM, but the incidence of FBM returned to the control level in a subsequent recovery hour. A moderate peripheral lactic acidosis does not blunt the inhibition of FBM evoked by acute hypoxemia and is not a likely explanation for the return of FBM during prolonged hypoxemia but actually might mediate some of the inhibition.

Acidosis, Lactic↗
PubMed2003

Identification of lactic acid bacteria isolated from human vaginal secretions.

A total of 57 lactic acid bacteria were isolated from the vaginal secretions of 259 patients. Of these strains, 37 were isolated from patients attending pre-natal clinics and the remaining strains from patients attending post-natal clinics. The strains were identified by using simple physiological and biochemical tests and their phenotypic relatedness determined by numerical analysis of total soluble cell protein patterns. The genotypic relatedness of representative strains selected from each of the protein profile clusters was determined by numerical analysis of the DNA banding patterns obtained from RAPD-PCR. The majority of lactobacilli isolated belonged to the species Lactobacillus pentosus, Lactobacillus fermentum and Enterococcus faecium. A few strains of Lactobacillus plantarum and Weissella viridescens were also isolated. One strain, TV 1029, grouped into the same protein profile cluster as E. faecium, but revealed a DNA banding pattern closer related to Enterococcus faecalis. This is the first report of W. viridescens associated with the human vagina.

Bacterial Proteins↗
PubMed1986

[Hormonal responses to repeated lactic acid anaerobic exercise in male subjects].

The hormonal response to repeated lactic acid anaerobic exercise was investigated in 6 young male adults. The exercise protocol consisted of 3 one-minute bouts of voluntary maximal effort, each bout being separated from the subsequent one by a two-minute rest period. Venous blood samples were obtained at rest and at the end of each of the 3 work bouts, as well as following 15 minutes of recovery. A marked increase in plasma catecholamine concentrations was observed in response to the repeated exercise bouts, the rise being more important for the adrenaline (x 22) than the noradrenaline (x 10) concentrations. A progressive increase in plasma somatotropin hormone was observed between the first and the last venous sampling. Moreover, a delayed rise in plasma cortisol, insulin, prolactin, and androstenedione was also observed. Hormonal concentrations of LH, FSH, DHEA-SO4, testosterone, SHBG and testosterone/SHBG ratio were not modified in response to the type of exercise.

Adult↗
PubMed2006

Simultaneous saccharification and L-(+)-lactic acid fermentation of protease-treated wheat bran using mixed culture of lactobacilli.

Protease-treated wheat bran (20% w/v) of particle size less than 300 microm containing 65% (w/w) starch was used for the simultaneous saccharification and L-(+)-lactic acid fermentation by the mixed cultures of Lactobacillus casei and Lactobacillus delbrueckii. Maximum lactate yield after various process optimizations was 123 g l(-1) with a productivity of 2.3 g l(-1) h(-1) corresponding to a conversion of 0.95 g lactic acid per gram starch after 54 h at 37 degrees C. By using protease-treated wheat bran around tenfold decrease in supplementation of the costly medium component, like yeast extract, was achieved together with a considerable increase in the production level.

Bioreactors↗
PubMed2005

Controlled functionalization of multiwalled carbon nanotubes with various molecular-weight poly(L-lactic acid).

Multiwalled carbon nanotubes (MWNT) were functionalized with poly(L-lactic acid) (PLLA) with different molecular weights using a "grafting to" technique. The oxidized MWNT (MWNT-COOH) were converted to the acyl-chloride-functionalized MWNT (MWNT-COCl) by treating them with thionyl chloride (SOCl2) and reacting them with PLLA to prepare the MWNT-g-PLLA. FTIR and Raman spectroscopy revealed that the PLLA was covalently attached to the MWNT, and the weight gain due to the functionalization was determined by thermogravimetric analyses (TGA). The Raman signals of the MWNT were greatly weakened as a result of the PLLA grafting. The morphology of the grafted PLLA was examined by using SEM and TEM. The amount of grafted PLLA depended on the molecular weight of the PLLA. The PLLA coated on the MWNT became thicker and more uniform with increasing PLLA molecular weight from 1000 to 3000. However, the amount of grafted PLLA became lower when the molecular weight of PLLA was further increased to 11,000 and 15,000, and the PLLA attached to the MWNT showed a squid leglike morphology forming blobs and leaving much of the MWNT surface bare.

Lactic Acid↗
PubMed2005

Study of the segmental dynamics in semi-crystalline poly(lactic acid) using mechanical spectroscopies.

The glass transition of poly(L-lactic acid) (PLLA) occurs not far above typical service temperatures (room or body temperatures) which has consequences on the material properties during its use, such as damping or the occurrence of structural relaxation. This work aims at characterising the glass transition dynamics of a semi-crystalline PLLA using both dynamic mechanical analysis (DMA) and thermally stimulated recovery (TSR). The main viscoelastic parameters have been characterised at 1 Hz using DMA and the master curve obtained after isothermal experiments at different temperatures provided a full picture of the solid-state rheological behaviour throughout a wide frequency range. The activation energies calculated from the shift factors agree with the TSR ones, exhibiting a maximum near the T(g). Above the T(g), the results can be described with the WLF model. In the glassy state, the activation energy decreases with decreasing temperatures being always higher than the prediction of the Adam and Gibbs theory, at least down to temperatures 30 degrees C below the T(g). This suggests the existence of non-arrested degrees of freedom in the glassy state, being consistent with the existence of a significant degree of cooperativity in the TSR results.

Glass↗
PubMed1999

Degradation of composite materials composed of tricalcium phosphate and a new type of block polyester containing a poly(L-lactic acid) segment.

Degradation of a new type of poly(L-lactic acid)/poly(ethylene; hexamethylene/ sebacate) block polyester and its composite containing 10 and 30 wt% tricalcium phosphate (TCP) were studied in vitro. Film specimens of thickness 100 and 250 microm for each of the three materials were immersed in phosphate buffered saline (pH 7.4) at 37 degrees C for up to 24 weeks. At appropriate intervals, water absorption, dry and wet tensile strength, molecular weight, and thermal properties of the specimens were measured by weighing, tensile strength testing, size exclusion chromatography, and differential scanning calorimetry, respectively. The decrease in tensile strength was greater in the unblended and thicker polymer film than in the other five films. The retention of tensile strength after 24 weeks increased with increasing TCP content. This trend was also noticed in the retention of molecular weight. The tensile strength of the materials having molecular weights below 5 x 10(4)-6 x 10(4) Mw or 2 x 10(4)-3 x 10(4) Mn dropped substantially and the materials became fragile. Blending of TCP to the PLLA block polyester retarded degradation, suggesting that TCP neutralized the carboxyl end groups formed by hydrolysis of ester bonds.

Absorption↗
PubMedDate not supplied

Transcatheter arterial embolization using poly-L-lactic acid microspheres.

PURPOSE: To assess the use of poly-L-lactic acid (PLLA) microspheres as an embolic material in transcatheter arterial embolization (TAE). MATERIALS AND METHODS: Between December 1993 and August 1995, eight patients [dural arteriovenous fistula (AVF) (n = 1), acute hemoptysis (n = 7)] underwent nine TAE procedures using PLLA microspheres. The patients were four men and four women, aged 38-82 years (mean, 62.4 years). All procedures were performed through a 3-F microcatheter inserted coaxially into a 5-F angiographic catheter via the right femoral artery. RESULTS: TAE using PLLA was technically successful in all patients. Flow stasis of the targeted arteries was obtained immediately after TAE. Clinical symptoms improved immediately after the procedure, and there was no recurrence during the follow-up period. Procedure-associated complications were not observed, except for slight fever up to 38 degrees C for three days that was managed conservatively. CONCLUSION: PLLA appeared to be a suitable embolic material for use in TAE when permanent occlusion is required. As PLLA particles can be prepared in any size, they are suitable for distal occlusion of arteries, thus avoiding proximal occlusion where the recruitment of collaterals is problematic.

Aged↗
PubMed2002

Lactic acid based PEU/HA and PEU/BCP composites: Dynamic mechanical characterization of hydrolysis.

Lactic acid based poly(ester-urethane) (PEU-BDI) and its composites with 20 and 40 vol.% bioceramic filler were characterized prior to their use as biocompatible and bioabsorbable artificial bone materials. Morphological, dynamic mechanical properties, and degradation of these either hydroxyapatite or biphasic calcium phosphate containing composites were determined. Addition of particulate bioactive filler increased the composite stiffness and the glass transition temperature, indicating strong interactions between the filler and matrix. Materials were sterilized by gamma-irradiation, which reduced the average molecular weights by 30-40%. However, dynamic mechanical properties were not significantly affected by irradiation. Specimens were immersed in 0.85 w/v saline at 37 degrees C for 5 weeks, and changes in molecular weights, mass, water absorption, and dynamic mechanical properties were recorded. All the composite materials showed promising dynamic mechanical performance over the 5 weeks of hydrolysis. Average molecular weights of PEU-BDI and its composites did not change substantially during the test period. PEU-BDI retained its modulus values relatively well, and although the moduli of the composite materials were much higher, especially at high filler content, they exhibited faster loss of mechanical integrity.

Antineoplastic Combined Chemotherapy Protocols↗
PubMedDate not supplied

[Gasometric studies and lactic acid determinations in arterial blood and cerebrospinal fluid in brain infarction].

In 54 cases of brain infarction and 17 control cases the gasometric parameters and lactic acid level were determined in arterial blood and cerebrospinal fluid. Metabolic acidosis was demonstrated in the arterial blood and cerebrospinal fluid. Respiratory acidosis compensated partly metabolic acidosis. Changes in the cerebrospinal fluid were more frequent and more pronounced, especially in cases with fatal outcome. Deep disturbances of acid-base balance complicated with hypoxia may have prosnostic significance while moderate rise in lactic acid level is without this significance.

Aged↗
PubMed1993

Detection, identification and characterization of bacteriocin-producing lactic acid bacteria from retail food products.

Forty bacteriocin-producing (Bac+) lactic acid bacteria (LAB) were isolated from food samples purchased from retail supermarkets and local farms. Of the 40 Bac+ isolates, 18 were isolated from 85 food samples by enrichment (21% isolation rate) whereas eight were obtained from 63 samples by direct plating (13% isolation rate). By direct plating, Bac+ LAB were detected at levels up to 2.4 x 10(5) cfu/g in ready-to-eat meats. The Bac+ isolates were identified by carbohydrate fermentation patterns, SDS-PAGE protein patterns, and other biochemical characteristics; SDS-PAGE proved invaluable in identifying strains that could not be identified by other means. Differential inhibitory spectra against indicator microorganisms assisted in the identification of 19 unique Bac+ isolates. Bac+ LAB included Enterococcus faecalis, Lactobacillus curvatus, Lb. delbrueckii, Lb. plantarum, Lactococcus lactis, and Pediococcus acidilactici. Lb. curvatus (four strains) and Lc. lactis (nine strains) were the only isolates inhibitory to foodborne pathogens including Listeria monocytogenes, Bacillus cereus, Clostridium perfringens and Staphylococcus aureus. Some Lc. lactis isolates inhibited as many as nine Gram-positive genera. Lb. curvatus FS47 and FS65 grew to high cell densities and produced bacteriocin at 6 degrees C; however, Lc. lactis FS56 produced greater levels of bacteriocin at lower cell densities. The high incidence of Bac+ LAB detected in retail foods indicates that the public is consuming a wide variety of Bac+ LAB that occur as natural contaminants. These data suggest a greater role for bacteriocins as biopreservatives in food.

Animals↗
PubMed2002

[Experimental research on degradation and biocompatibility of super-high-molecular-weight poly-DL-lactic acid].

OBJECTIVE: The super-high-molecular-weight poly-DL-lactic acid (PDLLA), with the molecular weight of 900 kD, is a newly emerging biomaterial and potentially used in the therapy of bone fracture because of its excellent mechanical property. However the biocompatibility of this material has not been reported so far, therefore this experiment was designed to examine whether the super-high-molecular-weight PDLLA was harmful to creatures, when it was implanted in the body of animals for a long period. METHODS: The material was prepared in small cuboids, with the size of 1.0 mm x 1.5 mm x 2.0 mm, and these blocks were implanted into the masseteric space of SD rats and, the activity of the SD-rats was monitored continuously. The animals were sacrificed in the 3rd, 6th, 9th, 12th months after the operation and, the specimens were taken out from the animals. The examination included anatomical, pathological and haematological methods. The data were analyzed with SPSS 8.0. RESULTS: The wound healed well after the operation. Super-high-molecular-weight PDLLA degraded 6 months after the implantation. In the 3rd month after the operation, a thin fiber membrane around the materials was formed. In the 6th month, the membrane was much thinner than that in the 3rd month and completely disappeared in the 9th month. The pathological examination showed that slightly inflammatory reaction appeared in the tissue around these blocks in the 3rd month, but the inflammatory reactions were gradually remitted in the following 6th, 9th and 12th months. Further, the haematological examination did not show any abnormity during the 12-month observation period. CONCLUSION: The super-high-molecular-weight PDLLA can be degrade when it is implanted into the body of creatures, which proves its good biocompatibility.

Animals↗
PubMed2006

Poly-L-lactic acid: consultation on the injection techniques.

OBJECTIVES: When poly-L-lactic acid (PLLA) was first introduced (marketed as New-Fill), incorrect injection technique was largely responsible for the manifestation of device-related adverse events in the form of subcutaneous papules and areas of induration. Now marketed as Sculptra, widespread clinical experience with injectable PLLA has resulted in a wealth of information on product reconstitution and correct injection technique. The injection techniques for the optimal use of injectable PLLA are detailed here. RESULTS: When injecting PLLA it is important to adhere to the product guidelines in terms of injection volume, depth and placement. As the material provides a gradual restoration of volume, PLLA should be injected conservatively, avoiding the possibility of overcorrection. Injections should be sufficiently deep to avoid areas of induration in the superficial layers of the dermis. Areas above hypermobile muscles should also be avoided to prevent localized coalescence of injected material. While utilization of a specific injection technique depends on the position and severity of the volume deficiency, all injections use a 26-gauge needle and are separated by 0.5-1.0 cm. In the lower face a 'criss-cross' and 'tunnelling' technique should be employed, depositing the material into the deep dermis at the junction with the hypodermis, followed by massage every 3-4 injections. Massage should be continued by the patient for at least a week following the treatment session. The 'criss-cross' and 'tunnelling' procedures involve the deposition of 0.1-0.2 mL of PLLA per injection. Material injected into the temple area should be deposited deep next to the bone with a 'depot' technique. Injections around the orbits or perioral region are possible, but should not be attempted without sufficient training. CONCLUSION: Adhering to the correct injection technique enables the physician to provide durable, natural-looking volume restoration with a very low incidence of device-related adverse events.

Adult↗
PubMedDate not supplied

The dynamics of changes in blood electrolyte and lactic acid concentrations, haematocrit, arterial blood pressure and heart rate in canoeists during 4 hours of rest after maximal effort.

In 12 canoeists determinations were carried out of the haematocrit value, and plasma concentrations of sodium, potassium and lactic acid during 4 hours of rest following maximal effort. The age of the sportsmen was from 18 to 21 years. The haematocrit was significantly increased immediately after the effort but in the first hour of restitution it fell below the resting value and increased then reaching the initial value only in the 4th hour. Serum lactic acid concentration increased in the first minutes of rest and then it decreased gradually reaching the resting value in the 4th hour. The concentration of sodium was not significantly changed throughout the whole period of restitution, when the haematocrit changes were taken into account. The concentration of potassium was very high immediately after the effort, but it fell below the resting value in the 15th minute, rose to the resting value in the 1st hour and in the 2nd hour it continued to rise much above the resting value, and only in the 4th it decreased again to the initial value. The author supposes that the second rise of the serum potassium level beginning in the 1st hour of restitution after maximal effort could be due to insufficient supply of ATP for maintaining the needs of the ionic pump or to secondary loss of water from the cells with a consequent rise in the intracellular hydrogen ion concentration.

Adolescent↗
PubMed2001

Growth of the bacteriocin-producing Lactobacillus sakei strain CTC 494 in MRS broth is strongly reduced due to nutrient exhaustion: a nutrient depletion model for the growth of lactic acid bacteria.

Although commercial MRS broth has been designed to allow excellent growth of lactobacilli, most of these bacteria are still subjected to a self-inhibiting process. The most likely explanation is the accumulation of lactic acid or other toxic end products and the depletion of nutrients. In this study, the self-inhibition of Lactobacillus sakei CTC 494 was analyzed in a kinetic way, and a nutrient depletion model was set up to describe the growth inhibition process. This simple model has considerable advantages compared to commonly used descriptive models such as the logistic growth equation. It offers a better fit and a more realistic description of the growth data by taking into account both growth inhibition due to lactic acid production and changes in growth rates due to nutrient depletion. Depending on the fermentation conditions, in MRS broth there appears to be a strong decrease of the specific growth rate over time. Some undefined compounds present in the complex nitrogen source of MRS broth appear to be of crucial importance because of their limited availability. Moreover, nutrient availability affects bacteriocin production through its effect on cell growth as well as on the bacteriocin production per cell. A plateau value for the bacteriocin production by L. sakei CTC 494 was observed.

Bacteriocins↗
PubMed2006

Antioxidative activities of soymilk fermented with lactic acid bacteria and bifidobacteria.

To further the goal of developing a probiotic dietary adjunct using soymilk, soymilk is fermented with lactic acid bacteria (Lactobacillus acidophilus CCRC 14079 or Streptococcus thermophilus CCRC 14085) and bifidobacteria (Bifidobacterium infantis CCRC 14633 or Bifidobacterium longum B6) individually, and in conjunction. We investigate several antioxidative activities including the inhibition of ascorbate autoxidation, the scavenging effect of superoxide anion radicals and hydrogen peroxide, and the reducing activity exerted by different varieties of fermented soymilks. In addition, the effect of spray-drying and freeze-drying on changes in antioxidative activity is examined. We find that in fermented soymilk both the inhibition of ascorbate autoxidation, and the reducing activity and scavenging effect of superoxide anion radicals varied with the starters used, but nevertheless are significantly higher than those found in unfermented soymilk. In general, antioxidative activity in soymilk fermented with lactic acid bacteria and bifidobacteria simultaneously is significantly higher (P < 0.05) than that fermented with either individually. Moreover, antioxidative activity increases as the fermentation period is extended. However, unfermented soymilk shows an H2O2-scavenging effect, while there is no scavenging effect except for the accumulation of H2O2 in fermented soymilk. Finally, we find that freeze-drying causes a significantly lesser (P < 0.05) reduction in the antioxidative activity of soymilk than does spray-drying. Irrespective of the drying method and the starters used for fermentation. The antioxidative activity of fermented soymilk reduces after drying yet remains higher than that of dried unfermented soymilk.

Antioxidants↗
PubMed2002

Widespread distribution of the bacteriocin-producing lactic acid cocci in Miso-paste products.

AIMS: A survey was conducted on the ecological distribution of bacteriocin-producing lactic acid bacteria in Miso-pastes, a typical fermented food in Japan. METHODS AND RESULTS Nine Miso-pastes were sampled for isolation of bacteriocin-producers. Almost all isolated enterococcal strains produced bacteriocins but no isolated tetragenococci did so. The bacteriocin-producing isolates were divided into nine groups by phenotypic tests. As the phenotypic characters were highly diverse, these strains could not be identified to species level on the basis of their phenotypes. The nine representative strains from each group were identified by 16S rRNA analysis. These bacteriocin-producers with one exception (Lactococcus sp.) were identified as strains of the Enterococcus faecium 'species group'. The bacteriocins of the nine strains were classified into five types according to their antibacterial spectral patterns and their SDS-PAGE profiles. The bacteriocins inhibited undesirable bacteria in Miso-pastes, such as Bacillus subtilis, but did not inhibit the useful Tetragenococcus halophila. CONCLUSIONS: The bacteriocin-producing lactic acid cocci were widespread at high frequencies in Miso-pastes. They were considered to play an important role in preventing the growth of undesirable bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: This study suggests that bacteriocin-producers act effectively as safe biopreservatives and may contribute to the biopreservation in Miso-pastes.

Bacteriocins↗