Foam separation is a simple and economic method for separation of surface-active molecules such as proteins and enzymes from aqueous solutions. In this study, lactic acid broth, spent brewer&rsquo / s yeast extract and residual beer was used to investigate the applicability and efficiency of foam separation technique in partial purification of fermentation products and recovery of valuable components from industrial waste streams. The effects of the process variables initial feed concentration, air flow rate, foaming time, liquid pool height and temperature on separation performance were studied and optimum conditions for removal of proteins from lactic acid broth was determined. Highest enrichment (172.2) and separation ratio (314) with a high protein recovery (45.2 %) were obtained by foaming 200 ml of lactic acid broth with an initial feed concentration of 0.018 mg/ml at an air flow rate of 38.5 cm3/min. Selectivity of foam separation in protein purification, and its effect on protein structure was investigated in brewery wastes using SDS-PAGE and native PAGE, respectively.

Rhizopus oryzae is a filamentous fungus, which can produce high amounts of L(+)-lactic acid and produces ethanol as the main by-product. In an effort to understand the pyruvate branch point of this organism, fermentations under different inoculum and glucose concentrations were carried out. At low inoculum size (1x103 spores ml-1), high amount of lactate (78 g l-1) was produced, whereas high ethanol concentration (37 g l-1) was obtained at high inoculum sizes (1x106 spores ml-1). Decreasing working volume increased lactate production significantly at high inoculum sizes (1x105 and 1x106 spores ml-1), but did not influenced the physiology at low inoculum sizes (1x103 and 1x104 spores ml-1). In shake flask cultures, at low initial glucose concentrations biomass yield was high and lactate and ethanol yields were low. Higher lactate and ethanol and lower biomass yields were obtained by increasing the initial glucose concentrations. In alginate immobilized, semi-continuous cultures with cell retention, glucose level in the medium was kept at low values. Like in shake flask cultures, as the glucose concentration decreased lactate and ethanol yields decreased and biomass yields increased. Increasing the glucose concentration by a pulse of glucose caused increases in branch point enzyme activities, as well as in concentrations of the metabolites. In fed batch cultures higher biomass yield (0.25 g DCW g glucose-1) could be obtained. Lactate dehydrogenase was influenced by the inoculum size and glucose concentration more than pyruvate decarboxylase and alcohol dehydrogenase. It showed higher activity at lactate producing fermentations. Unlike lactate dehydrogenase, pyruvate decarboxylase and alcohol dehydrogenase showed high activity even at low glucose concentrations.

The esterification of lactic acid with ethanol over Lewatit S 100, strong cation ion exchange resin catalyst, was studied in counter current vapor-liquid contactor type differential reactor by feeding ethanol and lactic acid solution as vapor and liquid phases, respectively. The ethanol vapor phase was diluted by dry air and the water removal was achieved by the mass transfer of water from liquid to vapor phase. Effect of ethanol to lactic acid feed molar ratio and vapor flow rate on fractional conversion and water removal efficiency were tested at 40-70&deg / C of column temperature range. It was observed that Lewatit S 100 was adequate catalyst for esterification of lactic acid with ethanol. Increase in ethanol to lactic acid feed molar ratio enhanced both lactic acid conversion and water removal by upper product stream. However, lactic acid conversion was suppressed by the increase of inlet vapor flow rate because of the decrease in ethanol concentration in gas phase which affected both esterification reaction rate and mass transfer rate. The reaction temperature is the other important parameter that affects the mass transfer of ethanol from vapor to liquid phase. Although reaction rate and equilibrium conversion values were promoted by temperature, the lower solubility of ethanol in liquid phase limited the fractional conversion while promoted the water mass transfer from liquid to vapor phase. The optimized vapor phase velocity and temperature can yield higher conversions than the equilibrium conversion at the same temperature and initial composition. Therefore, low pressure organic acids such as lactic acid can be successfully esterified by using counter current V-L contactor type reactors and by using integrated reaction and separation units.

Meniscus is a fibrocartilaginous tissue which plays an important role in joint stability, lubrication, and load bearing and transmission. Meniscal tears are commonly encountered in sports activities, or caused by degeneration of the cartilage with ageing. They lead to pain, loss of work, disturbed biomechanics of the knee and inability to walk or even move the legs. As the meniscal tissue is avascular in the inner portion, injury to this part does not heal by itself, and therefore treatments are needed. In some cases when complex tears occur, the tissue cannot be successfully treated with the conventional methods. Tissue engineering appears to be a promising alternative to treat such complex tears. It includes the application of cells on scaffolds (or cell carriers), and provision of bioactive agents to the site of injury in order to regenerate the damaged tissue. The cells and the bioactive agents are involved in the synthesis of the new tissue, while the scaffold acts as a support to guide the cells until the new tissue is formed, and it is slowly absorbed by the body leaving the new tissue behind. Thus, a natural tissue is generated at the end. Few studies have been reported on the tissue engineering of meniscus, but neither of them was able to completely mimic the meniscus structure, nor could they succeed in constructing scaffolds with sufficiently high tensile properties. In the current in vitro study, a novel 3D construct was proposed, in which the natural tissue is perfectly mimicked. The 3D construct consisted of aligned collagen fibers embedded within a foam network which stabilizes the structure. The foam was prepared by freezing a polymer solution with a certain concentration, and lyophilizing it. Aligned fibers were aimed to improve the tensile properties. The construct was impregnated in alginate gel, which was then crosslinked, to improve the compressive properties. The foam was prepared from (poly(L-lactic acid)/poly(lactic-co-glycolic acid) (PLLA/PLGA) solutions of various concentrations (2%, 2.5%, 3%, and 4% w/v) and at different freezing temperatures (-20oC or -80oC) to select the best preparation condition. After analysis of the microstructure and mechanical properties, foams prepared from 3% polymer solution frozen at -20oC were found to be the most appropriate for use as scaffold for the 3D construct, since they had large pores, high and interconnected porosity, as well as high mechanical strength. The 3D constructs were seeded with human meniscus cells and incubated for 21 days. Cell behavior on the constructs was examined. Cell attachment and proliferation was found to be better with the constructs not coated with alginate. However, the constructs coated with alginate demonstrated higher compressive strength. It was also found that incorporation of collagen fibers significantly improved the tensile properties. All the constructs were shown to lead to the production of extracellular components specific for fibrocartilages, and thus it was concluded that they were promising for use in meniscal replacement.

Severe sepsis and septic shock comprise a significant number of emergency department (ED) admissions annually. With the advent of early goal directed therapies, early identification and intervention have become paramount in this population. Few studies, however, have examined the role of serum lactate as a predictor of mortality or endpoint to resuscitation among this population. We aimed to show that improved lactate clearance is associated with decreased 28-day in-hospital mortality. We retrospectively examined data from the Yale Sepsis Registry for patients with severe sepsis or septic shock who had lactate levels that were measured initially in the ED and subsequently when the patient arrived on the floor. This study received institutional review board approval. Lactate clearance was calculated as a percentage, and comparison between patients who cleared lactate and those who did not were made for mortality data as well as baseline characteristics and interventions required between the two groups. 207 patients (110 male) with mean age and standard deviation (SD) of 63.17 ± 17.9 years were examined. 136 patients (65.7%) were diagnosed with severe sepsis and 71 patients (34.3%) had septic shock. Of those with identified sources of infection, pneumonia was the most common (54 patients, 26.1%). There were 171 patients in the clearance group and 36 patients in the non-clearance group, all of whom had a mean time of 9 hours 8 minutes ± 4 hours 6 minutes between lactate measurements. 28-day mortality rates were 15.2% (26 patients) in the lactate clearance group and 36.1% (13 patients) in the non-clearance group (p<0.01). Vasopressor support within 72 hours of admission was initiated among 61.1% (22 patients) in the non-clearance group compared with 36.8% (63 patients) in the clearance group (p<0.01). Mechanical ventilation was required for 36.3% (62 patients) in the clearance group and 66.7% (24 patients) in the non-clearance group (p=0.001). Rates of severe sepsis, mean number of SIRS and organ dysfunction criteria, and initial creatinine were similar between the two groups; however, only 86.1% (31 patients) in the non-clearance group received intravenous fluids in the ED compared with 98.8% (169 patients) in the clearance group (p=0.002). 33.3% (12 patients) in the non-clearance group had chronic obstructive pulmonary disease (COPD) compared with 15.2% (26 patients) in the clearance group (p<0.05). The mean Mortality in Emergency Department Sepsis (MEDS) scores were 8.78 ± 3.96 for the clearance group and 10.4 ± 4.48 for the non-clearance group (95% CI, -3.1 to -.14, p<0.05). These results show significantly higher mortality rates among patients who do not clear their lactate in the ED. Additionally, these patients require vasopressor support and mechanical ventilation more often. Lactate clearance was significantly associated with receipt of fluids and may also reflect lower MEDS score. Our findings suggest lactate clearance could be used as an endpoint for ED resuscitation and in stratifying mortality risk among patients with severe sepsis or septic shock. Future studies might seek to prospectively validate these findings and incorporate multivariate analysis to determine factors affecting lactate clearance.

Thesis (M.S.)--Mississippi State University. Department of Food Science Nutrition and Health Promotion. / Title from title screen. Includes bibliographical references.

The synthesis and characterization of a series of chiral indium complexes bearing a tridentate NNO ligand are reported. The ligand 2-[[[(dimethylamino)cyclohexyl]amino]methyl]- 4,6-bis(tert-butyl) phenol (H₂NNO) was synthesized via a previously published procedure and bound to indium by both a protonolysis and salt metathesis route. A dimethylated indium complex (NNO)InMe₂ (1) was isolated by reaction of InMe₃ with H₂NNO. A one-pot saltmetathesis route was used to produce a unique mixed-bridge dinuclear indium complex [(NNO)InCl] ₂(μ-OEt)(μ-Cl) (3) from a mixture of indium trichloride, potassium ethoxide and the monopotassiated salt of the ligand, KH(NNO). Direct reaction of KH(NNO) and indium trichloride resulted in the formation of (NNO)InCl₂ (4) which was carried forward to 3 by reaction with sodium ethoxide. The complex 3 is active for the ROP of β-butyrolactone ε-caprolactone and lactide and is the first reported indium-based catalyst for lactide or β-butyrolactone ROP. Kinetic studies of 3 for ROP of LA revealed that catalyst was well-behaved, and that the rate was first order with regard to lactide and catalyst. The enthalpy and entropy of activation for the ROP were experimentally determined. Polymer produced by ROP by 3 has narrow molecular weight distribution and a good correlation is seen between the observed moleular weight and monomer loading. A mechanism was proposed for 3 acting as a catalyst for the ROP of lactide; however further experiments are required to confirm this mechanism. Polymer samples isolated from the ROP of rac-lactide by rac-3 show isotactic enrichment. It is postulated that the chiral catalyst 3 is exerting stereocontrol via an enantiomorphic site control mechanism.

Lactic acid bacteria (LAB) are of interest because of their potential to modulate immune responses. The effects of LAB range from regulation to stimulation of the immune system. It has been reported that LAB affect health via two main mechanisms: directly through physical interactions between LAB and cells of the immune system, and indirectly through the products of these bacteria. The studies presented in this thesis examine the direct and indirect effects of LAB on the immune system specifically on murine dendritic cells (DCs). Mouse DCs (in form of the DC2.4 cell line) were treated in vitro with a fraction of bovine milk fermented with Lactobacillus helveticus-2 (LH-2) or three synthetic peptides identified within the fermented milk fraction. Cell culture supernatants were analyzed for presence of tumor necrosis factor (TNF)-α and interleukin (IL)-6 to determine the effects of LAB on DC activation. The results of this study showed that the ability of the milk derived fraction and the synthetic peptides to induce DC activation and production of pro-inflammatory cytokines was limited, suggesting that these peptides may induce regulatory immune responses. A series of studies was performed in vitro to investigate the effects of six LAB species and strains, (LH-2), Lactobacillus acidophilus-5 (La-5), Lactobacillus acidophilus-115 (La-115), Lactobacillus acidophilus-116 (La-116), Lactobacillus acidophilus-14 (La-14), and Lactobacillus salivarius, on maturation and activation of DC2.4. Production of TNF-α, IL-6 and IL-10 by DCs was determined after treating cells with live LAB. The expression of DC maturation markers, CD80 and CD40, was also measured using flow cytometry after stimulation with LAB. In addition, the expression of toll-like receptors (TLRs) 2, 4 and 9 by DCs stimulated with LAB was measured. Our results revealed that LAB act differentially on pro-inflammatory and anti-inflammatory cytokine production and induction of co-stimulatory molecules by DCs. Specifically, L. salivarius was found to be the most effective LAB to induce pro-inflammatory cytokine production and expression of co-stimulatory molecules. Moreover, La-14, La-116 and La-5 induced moderate maturation and activation of DCs. On the other hand, LH-2 and La-115 are the least likely lactobacilli to induce DC response. In conclusion, various strains and species of LAB can differentially regulate DC activation and maturation, raising the possibility that these microbes can influence and steer immune responses of the host.

No description available.

No description available.