12 research outputs found
Carbon dioxide uptake in a eutrophic stratified reservoir: Freshwater carbon sequestration potential
Carbon capture and storage due to photosynthesis activities has been proposed as a carbon sink to mitigate climate change. To enhance such mitigation, previous studies have shown that freshwater lakes should be included in the carbon sink, since they may capture as much carbon as coastal areas. In eutrophic freshwater lakes, there is uncertainty about whether the equilibrium equation can estimate the partial pressure of carbon dioxide (pCO2), owing to the presence of photosynthesis due to phytoplankton, and pH measurement error in freshwater fluid. Thus, this study investigated the applicability of the equilibrium equation and revealed the need to modify it. The modified equilibrium equation was successfully applied to reproduce pCO2 based on total alkalinity and pH through field observations. In addition, pCO2 at the water surface was lower than the atmospheric partial pressure of carbon dioxide due to photosynthesis by phytoplankton during strong stratification. The stratification effect on low pCO2 was verified by using the Net Ecosystem Production (NEP) model, and a submerged freshwater plants such as Potamogeton malaianus were found to have high potential for dissolved inorganic carbon (DIC) sequestration in a freshwater lake. These results should provide a starting point toward more sophisticated methods to investigate the effect of freshwater carbon on DIC uptake in freshwater stratified eutrophic lakes
Conventional osteosarcoma of the mandible successfully treated with radical surgery and adjuvant chemotherapy after responding poorly to neoadjuvant chemotherapy: a case report
Abstract Background Osteosarcoma, the most common primary bone malignancy, has an extremely poor prognosis and a high rate of local recurrence and distal metastases. Because osteosarcomas of the head and neck region are rare, accounting for less than 10% of all osteosarcoma cases, limited information is available about their treatment and prognosis. Because of the high rate of distal metastases associated with extragnathic osteosarcoma, surgery combined with chemotherapy is currently considered essential in its treatment. However, the role of chemotherapy has not been well elucidated in the treatment of head and neck osteosarcoma because of the rarity of this condition. Case presentation In this report, we present the case of a 58-year-old Japanese woman with osteosarcoma of the mandible that was treated with radical surgery combined with neoadjuvant and adjuvant chemotherapy. Because the tumor showed rapid growth during neoadjuvant chemotherapy, neoadjuvant chemotherapy was suspended and surgical resection was performed, followed by adjuvant chemotherapy. No evidence of local recurrence and distal metastasis was found 14 months after initial treatment. Local control is considered a principal prognostic factor for head and neck osteosarcoma. Conclusions Wide surgical excision should be considered a primary goal even during neoadjuvant chemotherapy, especially in cases that respond poorly to neoadjuvant chemotherapy
A novel vaccine strategy using quick and easy conversion of bacterial pathogens to unnatural amino acid-auxotrophic suicide derivatives
ABSTRACTWe propose a novel strategy for quick and easy preparation of suicide live vaccine candidates against bacterial pathogens. This method requires only the transformation of one or more plasmids carrying genes encoding for two types of biological devices, an unnatural amino acid (uAA) incorporation system and toxin-antitoxin systems in which translation of the antitoxins requires the uAA incorporation. Escherichia coli BL21-AI laboratory strains carrying the plasmids were viable in the presence of the uAA, whereas the free toxins killed these strains after the removal of the uAA. The survival time after uAA removal could be controlled by the choice of the uAA incorporation system and toxin-antitoxin systems. Multilayered toxin-antitoxin systems suppressed escape frequency to less than 1 escape per 109 generations in the best case. This conditional suicide system also worked in Salmonella enterica and E. coli clinical isolates. The S. enterica vaccine strains were attenuated with a >105 fold lethal dose. Serum IgG response and protection against the parental pathogenic strain were confirmed. In addition, the live E. coli vaccine strain was significantly more immunogenic and provided greater protection than a formalin-inactivated vaccine. The live E. coli vaccine was not detected after inoculation, presumably because the uAA is not present in the host animals or the natural environment. These results suggest that this strategy provides a novel way to rapidly produce safe and highly immunogenic live bacterial vaccine candidates.IMPORTANCELive vaccines are the oldest vaccines with a history of more than 200 years. Due to their strong immunogenicity, live vaccines are still an important category of vaccines today. However, the development of live vaccines has been challenging due to the difficulties in achieving a balance between safety and immunogenicity. In recent decades, the frequent emergence of various new and old pathogens at risk of causing pandemics has highlighted the need for rapid vaccine development processes. We have pioneered the use of uAAs to control gene expression and to conditionally kill host bacteria as a biological containment system. This report proposes a quick and easy conversion of bacterial pathogens into live vaccine candidates using this containment system. The balance between safety and immunogenicity can be modulated by the selection of the genetic devices used. Moreover, the uAA-auxotrophy can prevent the vaccine from infecting other individuals or establishing the environment
Developments in the Aerobic Oxidation of Amines
The oxidative upgrading of amines offers great opportunities for the sustainable production of key N-containing building-blocks for the modern chemical industry. Compared to other oxyfunctionalizations, and despite their potential, amine oxidation reactions are barely explored in the literature. This review aims at drawing attention to this important area and highlights both the major achievements and the challenges that still remain