Spent culture supernatant (SCS) of the probiotic Lactobacillus rhamnosus GG had been reported to exert antibacterial activity against Salmonella typhimurium. However, the chemical identity of the antimicrobial compound(s) responsible remained unknown. A survey of the antimicrobial compounds produced by L. rhamnosus GG was performed. Lactobacillus rhamnosus GG produced a low-molecular weight, heat-stable, non-proteinaceous bactericidal substance, active at acidic pH against a wide range of bacterial species. SCS of L. rhamnosus GG grown in MRS medium contained five compounds that could meet the above description, if present at the appropriate concentration. Based on different experimental approaches, it could be concluded that under the growth conditions tested, the strong antimicrobial activity of L. rhamnosus GG against Salmonella was mediated by lactic acid.

Growth factors have become an important component for tissue engineering and regenerative medicine. Insulin-like growth factor-I (IGF-I) and transforming growth factor-beta1 (TGF-beta 1) in particular have great significance in cartilage tissue engineering. Here, we describe sequential release of IGF-I and TGF-beta 1 from modular designed poly(l,d-lactic-co-glycolic acid) (PLGA) scaffolds. Growth factors were encapsulated in PLGA microspheres using spontaneous emulsion, and in vitro release kinetics was characterized by ELISA. Incorporating BSA in the IGF-I formulations decreased the initial burst from 80% to 20%, while using uncapped PLGA rather than capped decreased the initial burst of TGF-beta 1 from 60% to 0% upon hydration. The bioactivity of released IGF-I and TGF-beta 1 was determined using MCF-7 proliferation assay and HT-2 inhibition assay, respectively. Both growth factors were released for up to 70 days in bioactive form. Scaffolds were fabricated by fusing bioactive IGF-I and TGF-beta 1 microspheres with dichloromethane vapor. Three scaffolds with tailored release kinetics were fabricated: IGF-I and TGF-beta 1 released continuously, TGF-beta 1 with IGF-I released sequentially after 10 days, and IGF-I with TGF-beta 1 released sequentially after 7 days. Scaffold swelling and degradation were characterized, indicating a peak swelling ratio of 4 after 7 days of incubation and showing 50% mass loss after 28 days, both consistent with scaffold release kinetics. The ability of these scaffolds to release IGF-I and TGF-beta 1 sequentially makes them very useful for cartilage tissue engineering applications.

The gut microbiota is a complex community of bacteria residing in the intestine. Animal models have demonstrated that several factors contribute to and can significantly alter the composition of the gut microbiota, including genetics; the mode of delivery at birth; the method of infant feeding; the use of medications, especially antibiotics; and the diet. There may exist a gut microbiota signature that promotes intestinal inflammation and subsequent systemic low-grade inflammation, which in turn promotes the development of type 2 diabetes. There are preliminary studies that suggest that the consumption of probiotic bacteria such as those found in yogurt and other fermented milk products can beneficially alter the composition of the gut microbiome, which in turn changes the host metabolism. Obesity, insulin resistance, fatty liver disease, and low-grade peripheral inflammation are more prevalent in patients with low α diversity in the gut microbiome than they are in patients with high α diversity. Fermented milk products, such as yogurt, deliver a large number of lactic acid bacteria to the gastrointestinal tract. They may modify the intestinal environment, including inhibiting lipopolysaccharide production and increasing the tight junctions of gut epithelia cells.

Bacteria used in commercial probiotic preparations are most commonly gram-positive lactic acid-producing species, although there are also some probiotic products which utilise gram-negative coliform bacteria. Characterising how the innate immune system responds to these bacteria in vitro may give an indication as to the likely immunomodulatory events that can be triggered following probiotic administration in vivo. Here, an established gram-positive probiotic (Lactobacillus casei Shirota) was compared against a novel gram-negative probiotic strain (Escherichia coli Nissle 1917) for its ability to induce cytokine production in a cell type representative of the innate immune system; in addition, responses were contrasted against those induced by an enteropathogenic coliform, E. coli 2282. We investigated the ability of these three bacterial strains to modulate production of interleukins-10, -12 and -18; tumour necrosis factor-alpha; interferon-alpha; and transforming growth factor-beta, via a series of in vitro culture experiments involving the murine monocyte/macrophage cell line J774A.1. All bacteria induced marked secretion of IL-12 and TNFalpha by cells, while only coliforms induced production of IL-10; there was minimal or no induction of IL-18 or TGFbeta. Activation of cells with recombinant gamma-interferon promoted increased production of IL-12, but decreased production of IL-10, in response to the co-culture of coliform bacteria, indicating differential cytokine induction depending on the activation status of the target cell. In general, live bacteria stimulated higher levels of IL-10, IL-12 and TNFalpha secretion than heat-killed preparations, while only live coliforms induced IFNalpha. These findings are discussed in relation to the likely immunomodulatory effects of gram-positive and gram-negative bacteria on the innate immune system in vivo, with particular emphasis on the marked similarity in cytokine response patterns observed between probiotic versus pathogenic coliform bacteria.

OBJECTIVE

Panax ginseng C. A. Meyer (ginseng) is a well-known Chinese herb often used in Asian countries for physical strength development. Ginseng polysaccharides are its active component and have a lot of pharmaceutical activities. However, anti-fatigue activity of ginseng polysaccharides has not yet been tested. The current study was designed to evaluate the anti-fatigue activity of ginseng polysaccharides (WGP) in an animal test for fatigue and compare the activities between the neutral (WGPN) and acidic (WGPA) portion in an attempt to determine whether the medicinal uses are supported by pharmacological effects.

METHODS

WGP, WGPN and WGPA were orally administrated to mice once daily for 15 days. Anti-fatigue activity was assessed using the forced swim test (FST) and serum biochemical parameters were determined by autoanalyzer and commercially available kits.

RESULTS

While all compounds were found to reduce immobility in the FST, the effect of WGPA was demonstrated in lower doses compared with WGP and WGPN. Moreover, the FST-induced reduction in glucose (GLU) and glutathione peroxidase (GPx) and increase in creatine phosphokinase (CK), lactic dehydrogenase (LDH) and malondialdehyde (MDA) levels, all indicators of fatigue, were inhibited by the corresponding doses of WGP, WGPN and WGPA.

CONCLUSIONS

Ginseng polysaccharides have anti-fatigue activity, also reflected in the effects on the physiological markers for fatigue. The acidic polysaccharide is more potent than the neutral polysaccharide.

This study determined the difference in rate of degradation between pure polymers of lactic acid (pla), glycolic acid (PGA), and various ratios of copolymers of these two substances. Fast-cured and slow-cured polyglycolide was compared with copolymers of glycolide/lactide intermixed in ratios of 75:25, 50:50, and 25:75, as well as pure polylactide. A total of 420 rats were implanted with carbon-14 and tritium-labeled polymers in bone and soft tissue. At intervals of 1, 2, 3, 5, 7, 9, and 11 months, groups of five animals with the implants in bone and five with the implants in the abdominal wall were sacrificed. The implant area as well as tissue from the liver, spleen, kidney, lung and some muscle tissue was analyzed for radioactivity along with the urine and feces collected throughout the experiment. Half-lives of the different polymers and copolymers were calculated from the radioactivity present in the implant area for each time interval. Half-life of the polymers and copolymers decreased from 5 months for 100% PGA to 1 week with 50:50 PGA:PLA copolymer and rapidly increased to 6.1 months for 100% PLA. Fast-cured PGA had a half-life in tissue of 0.85 months. No difference in rate of degradation was seen in soft tissue or bone. No significant radioactivity was detected in urine, feces, or tissue samples. From this study, it is concluded that control of degradation rate of the implant could best be attained by varying the composition of PLA and PGA between 75% and 100% PLA along with a corresponding 25% to 0% PGA. This would provide a half-life range of the implant of from 2 weeks to 6 months.

More than 1200 isolates of lactic acid bacteria isolated from different environments were screened for antifungal activity in a dual-culture agar plate assay. Approximately 10% of the isolates showed inhibitory activity and 4% showed strong activity against the indicator mould Aspergillus fumigatus. The antifungal spectra for 37 isolates with strong activity and five isolates with low or no activity were determined. Several of the strains showed strong inhibitory activity against the moulds A. fumigatus, Aspergillus nidulans, Penicillium commune and Fusarium sporotrichioides, and also against the yeast Rhodotorula mucilaginosa. Penicillium roqueforti and the yeasts Pichia anomala and Kluyveromyces marxianus were not inhibited. Several isolates showed reduced antifungal activity after storage and handling. The majority of the fungal inhibitory isolates were identified by 16S rDNA sequencing as Lactobacillus coryniformis. Lactobacillus plantarum and Pediococcus pentosaceus were also frequently identified among the active isolates. The degree of fungal inhibition was not only related to production of lactic or acetic acid. In addition, antifungal cyclic dipeptides were identified after HPLC separation and several other active fractions were found suggesting a highly complex nature of the antifungal activity.

The wide application of lactic acid bacteria in the production of fermented foods depends to a great extent on the unique features of sugar metabolism in these organisms. The relative metabolic simplicity and the availability of genetic tools made Lactococcus lactis the organism of choice to gain insight into metabolic and regulatory networks. In vivo nuclear magnetic resonance has proven a very useful technique to monitor non-invasively the dynamics of intracellular metabolite and co-factor pools following a glucose pulse. Examples of the application of this methodology to identify metabolic bottlenecks and regulatory sites are presented. The use of this information to direct metabolic engineering strategies is illustrated.

Bionanocomposites formed by combining biodegradable polymers and nanosized osteoconductive inorganic solids have been regarded as promising biomimetic systems which possess much improved structural and functional properties for bone tissue regeneration. In this study three-dimensional nanocomposite scaffolds based on calcium phosphate (Ca-P)/poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) and carbonated hydroxyapatite (CHAp)/poly(l-lactic acid) (PLLA) nanocomposite microspheres were successfully fabricated using selective laser sintering, which is a rapid prototyping technology. The sintered scaffolds had controlled material microstructure, totally interconnected porous structure and high porosity. The morphology and mechanical properties of Ca-P/PHBV and CHAp/PLLA nanocomposite scaffolds as well as PHBV and PLLA polymer scaffolds were studied. In vitro biological evaluation showed that SaOS-2 cells had high cell viability and normal morphology and phenotype after 3 and 7 days culture on all scaffolds. The incorporation of Ca-P nanoparticles significantly improved cell proliferation and alkaline phosphatase activity for Ca-P/PHBV scaffolds, whereas CHAp/PLLA nanocomposite scaffolds exhibited a similar level of cell response compared with PLLA polymer scaffolds. The nanocomposite scaffolds provide a biomimetic environment for osteoblastic cell attachment, proliferation and differentiation and have great potential for bone tissue engineering applications.

OBJECTIVE

The purpose of this study was to determine the global transcriptional response in a food-associated lactic acid bacterium during bile stress.

RESULTS

Clone-based DNA micro-arrays were employed to describe the global transcriptional response of Lactobacillus plantarum WCFS1 towards 0.1% porcine bile. Comparison of differential transcript profiles obtained during growth of Lact. plantarum on plates with and without bile revealed 28 and 62 putative genes, of which the expression was at least 2.5-fold up- or down-regulated by bile, respectively. Approximately, 50% of these genes appeared genetically linked, and 12 bile-responsive gene clusters were identified. Seven of the identified bile-responsive genes and gene clusters encode typical stress-related functions, including glutathione reductase and glutamate decarboxylase, involved in oxidative and acid stress, respectively. Moreover, 14 bile-responsive genes and gene clusters were identified that encode proteins that are located in the cell envelope, including the dlt operon and the F1F0 ATPase.

CONCLUSIONS

The identification of a relatively high number of genes encoding cell envelope functions indicates a major impact of bile acids on the integrity and/or functionality of the cytoplasmic membrane and cell wall.

CONCLUSIONS

The data presented here provide valuable clues towards the defence mechanisms that play a role during bile stress in Lact. plantarum.

We found that intraperitoneal injection of organic acids, such as propionic and lactic acid, are able to develop writhing responses in mice similarly as that of acetic acid. These acid-induced writhing reactions were significantly attenuated by capsazepine, a VR1 receptor-specific antagonist, but the phenylbenzoquinone-induced one was not, suggesting that the acids but not phenylbenzoquinone activate the VR1 receptor, which is involved in polymodal pain perception. Hoe 140, a bradykinin B2 receptor antagonist, also suppressed the acid-induced writhing response. Furthermore, these writhing responses were significantly suppressed after neonatal treatment with capsaicin, which treatment is known to destroy peripheral sensory afferent C-fibers. Capsazepine and Hoe 140 did not further attenuate the already reduced writhing responses of capsaicin-treated mice, suggesting that the acids stimulate the VR1 and the bradykinin B2 receptor in the pathway comprising sensory afferent C-fibers. On the other hand, indomethacin further significantly suppressed the writhing number of the capsaicin-treated animals, suggesting that the acid-induced pain perception requires prostanoid receptors not only in the pathway via capsaicin-sensitive C-fibers but also in other sensory pathways. These results provide the first evidence for the involvement of the vanilloid receptor in the acid-induced inflammatory pain perception via sensory C-fibers in addition to the known mediators bradykinin, neurokinins, and prostanoids.

Bacteriocins from lactic acid bacteria are ribosomally produced peptides (usually 30-60 amino acids) that display potent antimicrobial activity against certain other Gram-positive organisms. They function by disruption of the membrane of their targets, mediated in at least some cases by interaction of the peptide with a chiral receptor molecule (e.g., lipid II or sugar PTS proteins). Some bacteriocins are unmodified (except for disulfide bridges), whereas others (i.e. lantibiotics) possess extensive post-translational modifications which include multiple monosulfide (lanthionine) bridges and dehydro amino acids as well as possible keto amide residues at the N-terminus. Most known bacteriocins are biologically active as single peptides. However, there is a growing class of two peptide systems, both unmodified and lantibiotic, which are fully active only when both partners are present (usually 1:1). In some cases, neither peptide has activity by itself, whereas in others, the activity of one is enhanced by the other. This review discusses the classification, structure, production, regulation, biological activity, and potential applications of such two-peptide bacteriocins.

The dental pathogen Streptococcus mutans persists and causes diseases in highly dynamic environments and gains a selective ecological advantage in environmental conditions that frequently exceed the limits for growth of the organism, particularly with regard to environmental pH. The goal of this study was to begin a molecular genetic analysis of a major stress protein, DnaK/Hsp70, to begin to understand how stress responses are regulated in this lactic acid bacterium and to establish a relationship between dnaK gene expression and exposure to acidic environments. Cloning and nucleotide sequence analysis revealed that the dnaK gene is preceded by, and is in an operon-like arrangement with, the hrcA and grpE genes, although intergenic spacing was unlike that described in other bacteria. An inverted repeat (a CIRCE element) was identified by sequence analysis and, using primer extensions, a heat shock-responsive, sigmaA-type promoter, P1, 5' to the hrcA gene, and a sigmaB-type promoter, 5' to the grpE translational start site, were identified. No promoters were detected between grpE and dnaK. A strain carrying a strongly polar insertion in the hrcA gene had markedly diminished levels of dnaK mRNA, indicating that dnaK was transcribed as part of an operon from P1, and to a lesser extent from P2. Results from physiological manipulation of S. mutans in continuous chemostat culture demonstrated that steadystate levels of S. mutans dnaK mRNA and DnaK protein were (i) increased in response to acid shock; (ii) elevated in acid 'adapted' cells; and (iii) induced in response to alkali shock of acid 'adapted' cells. In all cases, increased amounts of dnaK mRNA could be correlated with enhanced transcription from P1. This study provides the first detailed analysis of the expression of a heat shock gene from an oral isolate, and the evidence provided suggests that sigmaB-like promoters may also be involved in class I heat shock gene expression in some Gram-positive organisms.

Aligned, electrospun polymer fibers have shown considerable promise in directing regenerating axons in vitro and in vivo. However, in several studies, final electrospinning parameters are presented for producing aligned fiber scaffolds, and alignment where minimal fiber crossing occurs is not achieved. Highly aligned species are necessary for neural tissue engineering applications to ensure that axonal extension occurs through a regenerating environment efficiently. Axonal outgrowth on fibers that deviate from the natural axis of growth may delay axonal extension from one end of a scaffold to the other. Therefore, producing aligned fiber scaffolds with little fiber crossing is essential. In this study, the contributions of four electrospinning parameters (collection disk rotation speed, needle size, needle tip shape and syringe pump flow rate) were investigated thoroughly with the goal of finding parameters to obtain highly aligned electrospun fibers made from poly-L-lactic acid (PLLA). Using an 8 wt% PLLA solution in chloroform, a collection disk rotation speed of 1000 revolutions per minute (rpm), a 22 gauge, sharp-tip needle and a syringe pump rate of 2 ml h(-1) produced highly aligned fiber (1.2-1.6 microm in diameter) scaffolds verified using a fast Fourier transform and a fiber alignment quantification technique. Additionally, the application of an insulating sheath around the needle tip improved the rate of fiber deposition (electrospinning efficiency). Optimized scaffolds were then evaluated in vitro using embryonic stage nine (E9) chick dorsal root ganglia (DRGs) and rat Schwann cells (SCs). To demonstrate the importance of creating highly aligned scaffolds to direct neurite outgrowth, scaffolds were created that contained crossing fibers. Neurites on these scaffolds were directed down the axis of the aligned fibers, but neurites also grew along the crossed fibers. At times, these crossed fibers even stopped further axonal extension. Highly aligned PLLA fibers generated under optimized electrospinning conditions guided neurite and SC growth along the aligned fibers. Schwann cells demonstrated the bipolar phenotype seen along the fibers. Using a novel technique to determine fiber density, an increase in fiber density correlated to an increase in the number of neurites, but average neurite length was not statistically different between the two different fiber densities. Together, this work presents methods by which to produce highly aligned fiber scaffolds efficiently and techniques for assessing neurite outgrowth on different fiber scaffolds, while suggesting that crossing fibers may be detrimental in fostering efficient, directed axonal outgrowth.

There is an increasing scientific and commercial interest in the use of beneficial microorganisms, or "probiotics," for the prevention and treatment of disease. The microorganisms most frequently used as probiotic agents are lactic-acid bacteria such as Lactobacillus rhamnosus GG (LGG), which has been extensively studied in recent literature. Multiple mechanisms of action have been postulated, including lactose digestion, production of antimicrobial agents, competition for space or nutrients, and immunomodulation. We have reviewed recent studies of probiotics for the treatment and control of infectious diseases. Studies of pediatric diarrhea show substantial evidence of clinical benefits from probiotic therapy in patients with viral gastroenteritis, and data on LGG treatment for Clostridium difficile diarrhea appear promising. However, data to support use of probiotics for prevention of traveler's diarrhea are more limited. New research suggests potential applications in vaccine development and prevention of sexually transmitted diseases. Further studies are needed to take full advantage of this traditional medical approach and to apply it to the infectious diseases of the new millennium.

The role of the human microbiome in schizophrenia remains largely unexplored. The microbiome has been shown to alter brain development and modulate behavior and cognition in animals through gut-brain connections, and research in humans suggests that it may be a modulating factor in many disorders. This study reports findings from a shotgun metagenomic analysis of the oropharyngeal microbiome in 16 individuals with schizophrenia and 16 controls. High-level differences were evident at both the phylum and genus levels, with Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria dominating both schizophrenia patients and controls, and Ascomycota being more abundant in schizophrenia patients than controls. Controls were richer in species but less even in their distributions, i.e., dominated by fewer species, as opposed to schizophrenia patients. Lactic acid bacteria were relatively more abundant in schizophrenia, including species of Lactobacilli and Bifidobacterium, which have been shown to modulate chronic inflammation. We also found Eubacterium halii, a lactate-utilizing species. Functionally, the microbiome of schizophrenia patients was characterized by an increased number of metabolic pathways related to metabolite transport systems including siderophores, glutamate, and vitamin B12. In contrast, carbohydrate and lipid pathways and energy metabolism were abundant in controls. These findings suggest that the oropharyngeal microbiome in individuals with schizophrenia is significantly different compared to controls, and that particular microbial species and metabolic pathways differentiate both groups. Confirmation of these findings in larger and more diverse samples, e.g., gut microbiome, will contribute to elucidating potential links between schizophrenia and the human microbiota.

Metabolic acidosis frequently complicates sepsis and septic shock and may be deleterious to cellular function. Different types of metabolic acidosis (e.g., hyperchloremic and lactic acidosis) have been associated with different effects on the immune response, but direct comparative studies are lacking. Murine macrophage-like RAW 264.7 cells were cultured in complete medium with lactic acid or HCl to adjust the pH between 6.5 and 7.4 and then stimulated with LPS (Escherichia coli 0111:B4; 10 ng/ml). Nitric oxide (NO), IL-6, and IL-10 levels were measured in the supernatants. RNA was extracted from the cell pellets, and RT-PCR was performed to amplify corresponding mediators. Gel shift assay was also performed to assess NF-kappa B DNA binding. Inc easing concentrations of acid caused increasing acidification of the media. Trypan blue exclusion and lactate dehydrogenase release demonstrated that acidification did not reduce cell viability. HCl significantly increased LPS-induced NO release and NF-kappa B DNA binding at pH 7.0 but not at pH 6.5. IL-6 and IL-10 expression (RNA and protein) were reduced with HCl-induced acidification, but IL-10 was reduced much more than IL-6 at low pH. By contrast, lactic acid significantly decreased LPS-induced NO, IL-6, and IL-10 expression in a dose-dependent manner. Lactic acid also inhibited LPS-induced NF-kappa B DNA binding. Two common forms of metabolic acidosis (hyperchloremic and lactic acidosis) are associated with dramatically different patterns of immune response in LPS-stimulated RAW 264.7 cells. HCl is essentially proinflammatory as assessed by NO release, IL-6-to-IL-10 ratios, and NF-kappa B DNA binding. By contrast, lactic acidosis is anti-inflammatory.

The Wingate Anaerobic Test (WAnT) is generally used to evaluate anaerobic cycling performance, but knowledge of the metabolic profile of WAnT is limited. Therefore the energetics of WAnT was analysed with respect to working efficiency and performance. A group of 11 male subjects [mean (SD), age 21.6 (3.8) years, height 178.6 (6.6) cm, body mass 82.2 (12.1) kg] performed a maximal incremental exercise test and a WAnT. Lactic and alactic anaerobic energy outputs were calculated from net lactate production and the fast component of the kinetics of post-exercise oxygen uptake. Aerobic metabolism was determined from oxygen uptake during exercise. The WAnT mean power of 683 (96.0) W resulted from a total energy output above the value at rest of 128.1 (23.2) kJ x 30 s(-1) [mean metabolic power=4.3 (0.8) kW] corresponding to a working efficiency of 16.2 (1.6)%. The WAnT working efficiency was lower (P < 0.01) than the corresponding value of 24.1 (1.7)% at 362 (41) W at the end of an incremental exercise test. During WAnT the fractions of the energy from aerobic, anaerobic alactic and lactic acid metabolism were 18.6 (2.5)%, 31.1 (4.6)%, and 50.3 (5.1)%, respectively. Energy from metabolism of anaerobic lactic acid explained 83% and 81% of the variance of WAnT peak and mean power, respectively. The results indicate firstly that WAnT requires the use of more anaerobically derived energy than previously estimated, secondly that anaerobic metabolism is dominated by glycolysis, thirdly that WAnT mechanical efficiency is lower than that found in aerobic exercise tests, and fourthly that the latter finding partly explains discrepancies between previously published and the present data about the metabolic profile of WAnT.

The species Bifidobacterium lactis, with its main representative strain Bb12 (DSM 10140), is a yoghurt isolate used as a probiotic strain and is commercially applied in different types of yoghurts and infant formulas. In order to ensure the genetic identity and safety of this bacterial isolate, species- and strain-specific molecular tools for genetic fingerprinting must be available to identify isolated bifidobacteria or lactic acid bacteria from, e.g., various clinical environments of relevance in medical microbiology. Two opposing rRNA gene-targeted primers have been developed for specific detection of this microorganism by PCR. The specificity of this approach was evaluated and verified with DNA samples isolated from single and mixed cultures of bifidobacteria and lactobacilli (48 isolates, including the type strains of 29 Bifidobacterium and 9 Lactobacillus species). Furthermore, we performed a Multiplex-PCR using oligonucleotide primers targeting a specific region of the 16S rRNA gene for the genus Bifidobacterium and a conserved eubacterial 16S rDNA sequence. The specificity and sensitivity of this detection with a pure culture of B. lactis were, respectively, 100 bacteria/ml after 25 cycles of PCR and 1 to 10 bacteria/ml after a 50-cycle nested-PCR approach.

Pearl millet slurries, mixed with groundnuts or not, were chosen as a model to investigate the feasibility of obtaining a rapid overview of community structure and population dynamics of fermented foods using pyrosequencing of tagged 16S rRNA gene amplicons. From 14 fermented samples collected either in a traditional small-scale processing unit in Burkina Faso or at laboratory scale, 137,469 sequences of bacterial 16S rRNA gene amplicons were characterized. Except for a few Proteobacteria, almost all the bacterial sequences were attributed to cultivable bacteria. This approach enabled 80.7% of the sequences to be attributed to a family and 70% to a genus but did not enable identification to the species level. The bacterial sequences were assigned to four phyla, with Firmicutes representing the highest diversity, followed by Proteobacteria, Actinobacteria, and Bacteroidetes, which were found only in the slurries prepared in traditional production units. Most of the Firmicutes were lactic acid bacteria, mainly represented by members of the Lactobacillus, Pediococcus, Leuconostoc, and Weissella genera, whose ratio varied from the onset to the end of the fermentation. The other bacteria present at the beginning of fermentation were generally no longer detected at the end, which is consistent with already-known patterns in the microbial ecology of fermented foods. In conclusion, this method seems very promising for rapid and preliminary microbial characterization in many samples of an unknown food sample, by determining numerous nucleic sequences simultaneously without the need for cloning and cultivation-dependent methods.

Dental implants have 89% plus survival rates at 10-15 years, but peri-implantitis or dental implant infections may be as high as 14%. Peri-implantitis can limit clinical success and impose health and financial burdens to patients and health providers. The pathogenic species associated with periodontitis (e.g., Fusobacterium ssp, A. actinomycetemcomitans, P. gingivalis) are also associated with peri-implantitis. Incidence of peri-implantitis is highest within the first 12 months after implantation, and is higher in patients who smoke or have poor oral health as well as with calcium-phosphate-coated or surface-roughened implants. Biomaterial therapies using fibers, gels, and beads to deliver antibiotics have been used in the treatment of Peri-implantitis though clinical efficacy is not well documented. Guided tissue regeneration membranes (e.g., collagen, poly-lactic/glycolic acid, chitosan, ePTFE) loaded with antimicrobials have shown success in reosseointegrating infected implants in animal models but have not been proven in humans. Experimental approaches include the development of anti-bioadhesion coatings, coating surfaces with antimicrobial agents (e.g., vancomycin, Ag, Zn) or antimicrobial releasing coatings (e.g., calcium phosphate, polylactic acid, chitosan). Future strategies include the development of surfaces that become antibacterial in response to infection, and improvements in the permucosal seal. Research is still needed to identify strategies to prevent bacterial attachment and enhance normal cell/tissue attachment to implant surfaces.

OBJECTIVE

To investigate the hypothesis that occult hypoperfusion (OH) is associated with infectious episodes in major trauma patients.

METHODS

Data were collected prospectively on all adult trauma patients admitted to the Surgical/Trauma Intensive Care Unit from November of 1996 to December of 1998. Treatment was managed by a single physician according to a defined resuscitation protocol directed at correcting OH (lactic acid [LA]>> 2.4 mmol/L).

RESULTS

Of a total of 381 consecutive patients, 118 never developed OH and 263 patients exhibited OH. Seventeen patients were excluded because their LA never corrected, and they all subsequently died. One hundred seventy-six infectious episodes occurred in 97 of the 364 patients remaining. The infection rate in patients with no elevation of LA was 13.6% (n = 118) compared with 12.7% (n = 110) in patients whose LA corrected by 12 hours, 40.5% (n = 79; p < 0.01 compared with all other groups) in patients whose LA corrected between 12 and 24 hours, and 65.9% (n = 57; p < 0.01 compared with all other groups) in patients who corrected after 24 hours. Among the patients with infections, there were 276 infection sites with 42% of infections involving the lung and 21% involving bacteremia. There was no difference in proportion of infections occurring at each site between groups. The mortality rate of patients who developed infections was 7.9% versus 1.9% in patients without infections (p < 0.05). Of the patients who developed infections, 69.8% versus 25.8% (p < 0.001) did not have their lactate levels normalized within 12 hours of emergency room admission. Logistic regression demonstrated that both the Injury Severity Score and OH>> 12 hours were independently predictive of infection.

CONCLUSIONS

A clear increase in infections occurred in patients with OH whose lactate levels did not correct by 12 hours, with an associated increase in length of stay, days in surgical/trauma intensive care unit, hospital charges, and mortality.