ABSTRACT
Continuous anaerobic fermentations were performed in a biofilm reactor packed with Poraver® beads. Dilution rates (D) varied between 0.054 and 0.72 h(-1), and D-glucose and CO2 gas were used as carbon substrates. Steady-state conditions were shown to be repeatable and independent of the operational history. Production stability was achieved over periods exceeding 80 h at values of D below 0.32 h(-1). In these situations, steady-state variation (expressed as fluctuations in NaOH neutralisation flow rates) exhibited a standard deviation of less than 5 % while no indication of biofilm deactivation was detected. The total biomass amount was found to be independent of the dilution rate with an average dry concentration of 23.8 ± 2.9 g L(-1) obtained for all runs. This suggests that the attachment area controls the extent of biofilm accumulation. Specific succinic acid (SA) productivities, based on the total biomass amount, exhibited a substantial decrease with decreasing D. An SA volumetric productivity of 10.8 g L(-1) h(-1) was obtained at D = 0.7 h(-1)-the highest value reported to date in Actinobacillus succinogenes fermentations. SA yields on glucose increased with decreasing D, with a yield of 0.90 ± 0.01 g g(-1) obtained at a D of 0.054 h(-1). Production of formic acid approached zero with decreasing D, while the succinic to acetic acid ratio increased with decreasing D, resulting in an increasing SA yield on glucose.
Subject(s)
Actinobacillus/physiology , Biofilms/growth & development , Succinic Acid/metabolism , Actinobacillus/growth & development , Actinobacillus/metabolism , Anaerobiosis , Bacterial Adhesion , Biomass , Carbon Dioxide/metabolism , Formates/metabolism , Glucose/metabolismABSTRACT
The field of stem cell biology continues to evolve by characterization of further types of stem cells and by exploring their therapeutic potential for experimental and clinical applications. Human mesenchymal stem cells (hMSCs) are one of the most promising candidates simply because of their easiness of both ex vivo expansion in culture dishes and genetic manipulation. Despite many extensive isolation and expansion studies, relatively little has been done with regard to hMSCs' therapeutic potential. Although clinical trials using hMSCs are underway, their use in cancer therapy still needs better understanding and in vivo supporting data. The homing ability of hMSCs was investigated by creating a human xenograft model by transplanting an ovarian cancer cell line into immunocompromised mice. Then, genetically engineered hMSC-telo1 cells were injected through the tail vein and the contribution and distribution of hMSCs to the tumor stroma were investigated by immunohistochemistry and PCR specific to the telomerase gene. Results show that exogenously administered hMSCs preferentially home, engraft, and proliferate at tumor sites and contribute to the population of stromal fibroblasts. In conclusion, this study provides support for the capacity of hMSCs to home to tumor site and serve as a delivery platform for chemotherapeutic agents.
Subject(s)
Mesenchymal Stem Cells/physiology , Ovarian Neoplasms/therapy , Stromal Cells/cytology , Animals , Cell Line, Tumor , Cell Movement/physiology , Cell Proliferation , Female , Genetic Engineering/methods , Humans , Mesenchymal Stem Cells/cytology , Mice , Mice, Inbred NOD , Mice, Nude , Mice, SCID , Ovarian Neoplasms/metabolism , Ovarian Neoplasms/pathology , Telomerase/biosynthesis , Telomerase/genetics , Telomerase/metabolism , Xenograft Model Antitumor Assays/methodsABSTRACT
Determination of ochratoxin A (OTA) by immunoaffinity column clean-up and HPLC detection was performed on wheat and pig liver. Several extraction protocols involving methanol and ethyl acetate were investigated. The optimum experimental conditions for analysis of OTA in artificially contaminated wheat (87.4% recovery) using immunoaffinity column clean-up was found to be the methanol: PBS (1â¶1 v/v) protocol. These conditions, however, gave low recoveries for pig liver (40.4%).
ABSTRACT
A comprehensive survey of the consumption of intense sweeteners in Great Britain in 1988 quantified the levels of usage of different sweeteners and identified their distribution between food categories and population subgroups. Saccharin was found to be the most widely used intense sweetener. Beverages were the most common source of intense sweeteners. The quantities consumed of all sweeteners were found to be below the Acceptable Daily Intake (ADI) values established by the Joint FAO/WHO Expert Committee on Food Additives, the European Commission Scientific Committee for Food or the UK Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment.
Subject(s)
Sweetening Agents/administration & dosage , Adolescent , Adult , Aged , Aspartame/administration & dosage , Beverages , Child , Child, Preschool , Diet Surveys , Humans , Infant , Maximum Allowable Concentration , Middle Aged , Saccharin/administration & dosage , United KingdomABSTRACT
The nomenclature relating to structures at the distal part of the nail is confusing. A distal yellow line traversing the nail, described by Pinkus, has been relatively ignored in the literature and remains unnamed. Clinical and histological studies presented in this article show that this band is present in more than 90% of normal adult fingernails and represents the most proximal point of attachment of the fingertip stratum corneum to the nail plate. Therefore, it should be referred to as the onychocorneal band or junction. This region has distinctive histological features and is the first major barrier to material passing proximally beneath the nail plate. It is possible that abnormalities of this structure may result in onycholysis, pachyonychia congenita, and pterygium inversum unguis.
