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PubMedDate not supplied

Controlled release of cisplatin incorporated into biodegradable poly-d, l-lactic acid.

Using a melt-pressing technique, we produced a small solid cylinder containing cisplatin (CDDP) embedded in poly-d, l-lactic acid (CDDP-PLA). The in vitro release of CDDP from the polymer was examined in an immersion system. CDDP was released continuously for more than four weeks with no initial burst. Drug distribution for CDDP-PLA was compared with CDDP solution (CDDP-SOL) by subcutaneous administration into the back of rats. In the CDDP-PLA group, a high concentration of CDDP was maintained in the subcutaneous tissues near the implants for 20 days. However, in the CDDP-SOL group, the concentration of CDDP was low by 10 days after drug administration. CDDP-PLA may become a useful tool in locoregional chemotherapy as a solid type of drug delivery system with longlasting release.

Animals↗
PubMed2004

Immobilization of chitosan onto poly-L-lactic acid film surface by plasma graft polymerization to control the morphology of fibroblast and liver cells.

Surface functionalization of biodegradable poly-L-lactic acid (PLLA) was achieved by plasma coupling reaction of chitosan. The structure of modified PLLA surfaces was characterized by contact angle measurements and X-ray photoelectron spectroscopy. Two cell lines, L929 (mouse fibroblasts) and L02 (human hepatocytes), were cultured on the modified PLLA surface. It was found that cells cultured on this film could hardly spread and tend to become round, and the film was demonstrated to be a poorly adhering substrate. However, cells grown on this substrate can proliferate at almost the same speed as cultured on a glass surface. These results suggest that the new substrate can be used to control the morphology of cells, and has potential applications in tissue engineering. It may be helpful in understanding the mechanism of the switch between cell phases of growth and differentiation, which is necessary for the design of tissue regeneration biomaterials.

Adsorption↗
PubMed2000

Bacterial adherence to ofloxacin-blended polylactone-coated self-reinforced L-lactic acid polymer urological stents.

OBJECTIVE: To determine whether ofloxacin coating has any effect on bacterial adherence to bioresorbable self-reinforced L-lactic acid polymer (SR-PLLA) urological stents. MATERIALS AND METHODS: SR-PLLA stents were coated with epsilon-caprolactone/L-lactide copolymer blended with ofloxacin at three different concentrations of ofloxacin (0.5, 2 and 5% w/w). The adherence of five bacterial strains (Pseudomonas aeruginosa, Enterococcus faecalis, Proteus mirabilis and two strains of Escherichia coli) to the coated SR-PLLA stents was analysed. Uncoated stent pieces were used as controls. The effect of ofloxacin coating on bacterial growth in the microenvironment of the stent pieces was also analysed. RESULTS: Ofloxacin coating prevented bacterial adherence to SR-PLLA stent material; this effect correlated significantly with the ofloxacin concentration of the caprolactone coating. Ofloxacin coating reduced the amount of bacteria in the microenvironment of the stent, but because of natural resistance, ofloxacin coating had little effect on E. faecalis. CONCLUSION: Except for E. faecalis, ofloxacin coating may reduce stent-associated infections. However, further studies are needed to confirm its biocompatibility and efficacy in clinical use.

Anti-Infective Agents, Urinary↗
PubMed2001

Role of vagal C-fiber afferents in the bronchomotor response to lactic acid in the newborn dog.

We addressed the hypothesis that vagal C-fiber afferents and cyclooxygenase products are the mechanisms responsible for lactic acid (LA)-induced bronchoconstriction in the newborn dog. Perineural capsaicin and indomethacin were used to block conduction of vagal C fibers and production of cyclooxygenase products, respectively. Perineural capsaicin eliminated (85%) the increase in lung resistance (RL; 45 +/- 5.6%) due to capsaicin (25 microg/kg), whereas the increase in RL (54 +/- 6.9%) due to LA (0.4 mmol/kg) was only inhibited by 37 +/- 4.7% (P < 0.05). Atropine reduced LA-induced bronchoconstriction (42 +/- 2.1%) by an amount similar to that obtained with perineural capsaicin. However, inhibition was significantly increased when atropine was combined with indomethacin (61 +/- 2.7%; P < 0.05), implicating cyclooxygenase products in the LA-induced bronchoconstrictor response. We conclude that the mechanisms responsible for LA-induced bronchoconstriction in the newborn are 1) activation of vagal C-fibers, which, through projections to medullary respiratory centers, leads to activation of vagal cholinergic efferents; 2) production of cyclooxygenase products, which cause bronchoconstriction independent of medullary involvement; and 3) an unknown bronchoconstrictor mechanism, putatively tachykinin mediated. On the basis of our data, pharmaceutical targeting of pulmonary afferents would prevent multiple downstream mechanisms that lead to airway narrowing due to inflammatory lung disease.

Animals↗
PubMed2006

[Treatment of hepatocellular carcinoma in mice with locally administered epirubicin-loaded poly(D, L)-lactic acid microspheres].

OBJECTIVE: To study the effectiveness of treating hepatocellular carcinoma (HCC) in mice with locally administered epirubicin-loaded poly( D, L) - lactic acid microspheres (EPI-PLA-MS ). METHODS: EPI-PLA-MS was prepared with double emulsion solvent evaporation technique. Five groups of mice (n = 8 in each group) were intraperitoneally injected with five different doses of free epirubicin (FEPI), and the maximum tolerated dose (MTD) was calculated. Then 15 mice with transplanted subcutaneous H22 HCC were divided into three groups (n = 5), which were respectively intratumorally injected with normal saline (NS), blank microspheres, and EPI-PLA-MS (with 9 mg/kg of EPI). After two weeks the tumors were excised and weighed. Another 15 mice with transplanted H22 ascites HCC were divided into three groups (n = 5), which were intraperitonealy injected with the same drugs, and the increased life span were registered exactly. RESULTS: The MTD of intraperitoneally injected FEPI was 9 mg/kg. The tumour-inhibiting rates was 40.35% and 36.09% when EPI-PLA-MS were administered by intratumoral injection to the mice with subcutaneous H22 HCC. It significantly prolonged the survival time of mice with H22 ascites HCC and the increased life span by 153.49% and 142.22% when EPI-PLA-MS were intraperitoneally administered. CONCLUSION: EPI-PLA-MS is a new sustained-release preparation with high-efficacy and low-toxicity in treating HCC and has shown promising prospects when administered locally.

Animals↗
PubMed2006

MRI study of bioabsorbable poly-L-lactic acid devices used for fixation of fracture and osteotomies.

BACKGROUND: The overall clinical results of bioabsorbable fixation devices made of poly-L-lactic acid (PLLA) used for fixation of fractures, bone grafting, and osteotomies have been favorable. However, clinical studies demonstrated no sign of normal bony architecture restored after surgery, although implant channels had been filled with fibrous tissue. The purpose of the present retrospective study was to examine the extent of structural changes in PLLA devices (PLLA-Ds) for fixation of rotational acetabular osteotomies and displaced malleolar ankle fractures using magnetic resonance imaging (MRI). METHODS: Altogether, 14 patients with osteoarthritis of hip joints and 15 with displaced malleolar ankle fractures were operated on using PLLA-D (NEOFIX). Of these patients, 22 were finally enrolled in the study, and the period from operation to the time of the study ranged from 17 to 78 months. The postoperative radiographic findings were evaluated for union, and changes around the implant holes were classified as sclerosis, resorption, or no change. MRI was carried out to estimate changes in the PLLA-Ds. RESULTS: Bone union was obtained in all cases; clinical complications such as infection, joint effusion, soft tissue irritation due to PLLA-D deviation, and motion pain in the joints were not observed. The MRI study suggested that water content in PLLA-D increased mainly due to biodegradation and that implants were not replaced by bony tissue. CONCLUSIONS: The PLLA-Ds were degraded but were not replaced by bony tissue during the observation period. Considering these findings and the assumption that in bony tissues mechanical strength of PLLA-D decreases with time, attention should be paid to mechanical insufficiency, which may occur when the cross-sectional area of a PLLA-D extends beyond the cross-sectional area of the osteosynthesis site.

Absorbable Implants↗
PubMed1994

13C NMR study of C2- and C3-deuterated lactic acid production by parotid cells exposed to 13C-labeled glucose in the presence of D2O.

The generation of C2- and C3-deuterated lactic acid produced by rat parotid cells exposed to [1-13C] glucose, [2-13C]glucose, and [6-13C]glucose in the presence of D2O was assessed by 13C NMR. The results indicated that the escape from deuteration amounted to about 46% at the phosphoglucoisomerase level, 100% at the phosphomannoisomerase level, 65% in the reactions catalyzed by phosphofructoaldolase and triose phosphate isomerase, and 58% at the level of glutamate pyruvate transaminase. Such high values are considered to support a possible enzyme-to-enzyme tunneling of metabolic intermediates at selected sites in the glycolytic pathway.

Animals↗
PubMed1997

Efficacy of carbon dioxide, 1-octen-3-ol, and lactic acid in modified Fay-Prince traps as compared to man-landing catch of Aedes aegypti.

The attractants 1-octen-3-ol and lactic acid significantly decreased catches of Aedes aegypti in Townsville, Australia, by 50% in a controlled laboratory environment and by 100% in the field when compared to carbon dioxide baited bidirectional Fay-Prince trap catches. Evaluation of an omnidirectional alteration on a bidirectional Fay-Prince trap revealed no significant improvement in catch size when compared to both the bidirectional trap and man-landing catch (MLC). Cumulative evening MLC (1730-2000 h) was twice that of the morning MLC (0600-0830 h), which has implications on the precise estimation of the man-biting rate. The MLC sampling method is shown to be a quick, simple, effective and cheap alternative to expensive traps in areas not currently experiencing arbovirus transmission.

Aedes↗
PubMed2001

Preparation and evaluation of poly(L-lactic acid) microspheres containing rhEGF for chronic gastric ulcer healing.

Biodegradable microspheres containing recombinant human epidermal growth factor (rhEGF) were prepared using poly(L-lactic acid) by a solvent evaporation method based on multiple w/o/w emulsion. Encapsulation efficiency and initial release were influenced by the amount of polymer, inner water phase volume and osmotic pressure difference between inner water phase and outer water phase. The effect of osmotic pressure difference between inner water phase and outer water phase in w/o/w emulsion on particle size, porosity and in vitro release of rhEGF from microspheres were also studied. Microspheres prepared with the optimized osmotic pressure, polymer amount and inner water volume produced 21% initial release on the first day with 92% encapsulation efficiency. The blood concentration of rhEGF was maintained at constant levels for 9-11 days after a single subcutaneous (s.c.) administration of rhEGF microspheres. The gastric ulcer healing effect of a single s.c. administration of rhEGF microspheres was increased 1.44-fold compared with twice a day s.c. administration of rhEGF saline solution after 11 days. The enhanced curative ratio of rhEGF loaded microspheres may be due to the optimized osmotic pressure, high encapsulation efficiency and sustained release pattern.

Animals↗
PubMed1997

A computerised system for the identification of lactic acid bacteria.

A generic computerised system for the identification of bacteria was developed. The system is equipped with a key to the identification of lactic acid bacteria. The identification is carried out in two steps. The first step distinguishes groups of bacteria by following a decision tree with general identification tests. The second step in the identification is the distinction of species within a group on the basis of biochemical fermentation patterns. During grouping, probabilities for test failure are used. These probabilities can be used for assessing the quality of a given test answer. The probabilities are also used to select the most probable test answer in cases where the test result is inconclusive. The probabilities of test failure were determined by a group of experts and a group of potential users of the identification system. During species identification, similarity indices are calculated for all bacteria in a group. The described identification system has the ability to "learn" from different sessions in the species identification step, improving both identification speed and accuracy. Because of the versatile way in which the system is set up, it can very easily be expanded with identification keys to other organisms.

Carbohydrate Metabolism↗
PubMed2004

Antitumor characteristics of methoxypolyethylene glycol-poly(DL-lactic acid) nanoparticles containing camptothecin.

The novel nanoparticles (CPT-NP) were prepared by the solvent evaporation method using methoxypolyethylene glycol-poly(DL-lactic acid) block copolymer as a matrix and camptothecin (CPT) as an antitumor agent, and the antitumor characteristics were examined in vitro and in vivo. The mean diameter of CPT-NP was approximately 250 nm. The drug release from CPT-NP in phosphate-buffered saline, pH 7.4, depended on the particle concentration; in the diluted condition, the initial rapid release was greater and subsequent gradual release was faster. After i.v. administration (0.5 mg CPT eq./kg) in rats, CPT-NP showed a longer plasma retention than CPT solution. In both single (2.5 mg CPT eq./kg) and double (2.5 mg CPT eq./kg x 2) administration to mice bearing sarcoma 180 solid tumor, CPT-NP were much more effective than CPT solution; especially, the tumor disappeared completely in three of the four mice in twice administration of CPT-NP, when the body weight did not decrease markedly. After i.v. administration to the tumor-bearing mice, CPT-NP showed better plasma retention, and high and long tumor localization. CPT-NP are suggested to greatly improve the efficacy of CPT due to their pharmacokinetic features.

Animals↗
PubMed2004

Poly(lactic acid) nanoparticles labeled with biologically active Neutravidin for active targeting.

In this study, NeutrAvidin was covalently bound to the surface of poly(DL-lactic acid) (PLA) nanoparticles, with the aim of attaching targeting compounds, such as proteins, to their surface. Sulfhydryl groups were first introduced on the surface of PLA nanoparticles through a carbodiimide reaction. NeutrAvidin was then bound to the thiolated nanoparticles via a bifunctional cross-linker, which offers two binding sites, one for primary amine groups and one for thiol functions. The amount of sulfhydryl groups obtained on the surface of the nanoparticles was determined. The NeutrAvidin -labeled nanoparticles were evaluated with respect to particle size, protein concentration and biotin binding capacity. The concentration of thiol functions on the surface of nanoparticles was 105 +/- 15 mmol/mol PLA. The quantification of NeutrAvidin coupled to the nanoparticles revealed that a significant amount of the protein was covalently bound to the nanoparticles. The concentration of NeutrAvidin bound to the nanoparticles could be controlled by varying the amount of protein during the coupling reaction. The maximum concentration of NeutrAvidin attached to the particles was 6 mmol per mol of PLA. The specific activity of NeutrAvidin bound to the nanoparticles was also evaluated and results revealed that the protein maintained the capacity to bind biotin. The activity of the NAR-labeled nanoparticles was lower than expected, due to the undesired aggregation of the native NeutrAvidin. Altogether, the results suggest that other proteins, such as antibodies could be coupled to the nanoparticles for active targeting. Furthermore, PLA nanoparticles bearing NeutrAvidin are interesting candidates for active targeting with biotinylated antibodies using the biotin-avidin interaction in a two step procedure.

Avidin↗
PubMed1984

Effect of dietary propionic and lactic acids on feed intake by chicks.

Two organic acids were evaluated for their potential to regulate feed intake of chicks by dietary means. When propionic acid was included in the feed up to levels of 100 g/kg, from 0 to 28 days, voluntary feed intake of chicks was decreased with increasing dietary levels of acid. Propionic acid had a greater effect per unit weight when included in drinking water as compared with inclusion in feed. Lactic acid, up to 30 g/kg, did not significantly reduce feed intake.

Animals↗
PubMed1992

The ability of the ropy slime-producing lactic acid bacteria to form ropy colonies on different culture media and at different incubation temperatures and atmospheres.

The ability of the ropy slime-producing lactic acid bacteria to form ropy colonies aerobically and anaerobically on APT, MRS, MRS-S and Rogosa SL agars at 15, 20 and 30 degrees C was tested. Wide variation was observed in the proportion of ropy colonies produced with different culture methods and different test periods. The percentage of viscous colonies was usually highest at 15 degrees C. No suitable uniform method for all strains was found; and the results varied according to the bacterial strain studied. For testing purposes, use of the method producing the highest proportion of ropy colonies for each bacterial strain is recommended.

Culture Media↗
PubMed2003

Reduction of noise-stress-induced physiological damage by radices of Astragali and Rhodiolae: glycogen, lactic acid and cholesterol contents in liver of the rat.

Noise is one of the factors that induces critical stress in animals. The contents of glycogen, lactic acid and cholesterol in the liver of noise-stressed rats were analyzed in order to investigate the alleviation of noise-stress-induced physiological damages by traditional medicine using Astragali and Rhodiolae radices. More than 95 dB noise ranging from 2 to 4 kHz reduced the contents of these compounds in the liver of rats not injected with the extract of Astragali or Rhodiolae, but did not change the contents in the liver of rats injected with the Astragali or Rhodiolae extract. These results show that noise induced stress in the rats via a decrease in contents of these compounds in the liver and that Astragali or Rhodiolae maintained the contents of these compounds in the liver of the noise-stressed rats. The results indicate that Astragali or Rhodiolae improved the ability for rats to resist noise stress.

Animals↗
PubMed2006

Lactic acid bacteria increase antiallergic effect of Artemisia princeps pampanini SS-1.

Artemisia princeps Pampanini, which is called Ssajuarissuk in Korean (SS-1), was fermented with lactic acid bacteria (LAB) and their passive cutaneous anaphylaxis reaction-inhibitory activity was investigated. Of these fermented agents, SS-1 extract fermented with Bifidobacterium infantis K-525 (F-SS-1) most effectively inhibited the release of P-hexosamindase from RBL-2H3 cells induced IgE. In IgE-induced RBL-2H3 cells, F-SS-1 inhibited proinflammatory cytokines IL-6 and TNF-alpha mRNA expression. Oral administration of SS-1 and F-SS-1 to mice inhibited passive cutaneous anaphylaxis (PCA) reaction induced by IgE and scratching behaviors induced by compound 48/80. The inhibitory activity of F-SS-1 against scratching behaviors was more effective than that of SS-1. These findings suggest that the fermentation of SS-1 with LAB can increase its antiallergic activity.

Animals↗
PubMed2003

The effect of Lactobacillus buchneri, with or without homofermentative lactic acid bacteria, on the fermentation, aerobic stability and ruminal degradability of wheat, sorghum and maize silages.

AIMS: To determine the effect of Lactobacillus buchneri, alone or in combination with homofermentative lactic acid bacteria (LAB), on the fermentation, aerobic stability and ruminal degradability of wheat, sorghum and maize silages. METHODS AND RESULTS: The inoculants were applied at 1.0 x 10(6) CFU g(-1). Silages with no additives served as control. Three jars per treatment were sampled on days 2, 4, 8, 15 and 60 after ensiling, for chemical and microbiological analysis. At the end of the ensiling period, the silages were subjected to an aerobic stability test. The L. buchneri- and L. buchneri + L. plantarum-inoculated silages had significantly higher levels of acetic acid than the control and L. plantarum-inoculated silages (P<0.05). Therefore, yeast activity was impaired in the L. buchneri- and L. buchneri + L. plantarum-inoculated silages. As a result, L. buchneri, with or without L. plantarum, improved aerobic stability of the silages. The combination of L. buchneri and L. plantarum reduced pH, ammonia-N, and fermentation losses in the silages. However, L. buchneri, L. plantarum and L. buchneri + L. plantarum did not affect in situ dry matter, organic matters, and neutral detergent fibre degradability of the silages. CONCLUSIONS: The L. buchneri was very effective in protecting the wheat, sorghum and maize silages exposed to air under laboratory conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of L. buchneri, with or without homofermentative LAB, as a silage inoculant can improve the aerobic stability of silages by inhibition of yeast activity.

Acetic Acid↗
PubMed1998

Intra nasal administration of poly-lactic acid microsphere co-encapsulated Yersinia pestis subunits confers protection from pneumonic plague in the mouse.

Equivocal doses of soluble, or high molecular weight poly (lactic acid) microsphere co-encapsulated, F1 and V subunit antigens of Yersinia pestis were used to immunize mice intra-nasally. Animals were dosed on day 1 and 7 with 2.724 micrograms V plus 0.956 micrograms F1. Co-encapsulated antigens induced superior systemic and mucosal immunity in comparison with free F1 and V. All of the mice immunized with soluble antigens died shortly after an aerosol challenge consisting of 1 x 10(5) colony-forming units of plague bacteria. In contrast, 66% of the co-encapsulated subunit vaccinees survived this lethal challenge. Humoral immunity to plague was improved further, resulting in 80% protection from challenge, if a relatively high dose (10 micrograms) of cholera toxin B subunit was added to the microsphere suspension prior to intra-nasal delivery. Significantly, by adding 10 micrograms cholera toxin B subunit to the free antigen solution, a 100% post-challenge survival rate was attained. We conclude that in this animal model of pneumonic plague, intra-nasal administration of microgram quantities of Yersinia pestis subunits confers protective immunity, provided the vaccines are microencapsulated or admixed with a strong mucosal adjuvant, such as the cholera toxin B subunit.

Administration, Intranasal↗