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991.
van de Lagemaat R van Koppen CJ Krajnc-Franken MA Folmer BJ van Diepen HA Mulders SM Timmers CM 《Reproduction (Cambridge, England)》2011,142(6):893-905
During recent decades minor innovative drugs have been developed for the female contraceptive market and they all contain steroidal progestagens (and estrogens) that act centrally and have side effects that can be attributed to this central action. In this study, we present an innovative tissue-specific approach for female contraception by low molecular weight (LMW) FSH receptor (FSHR) agonists, which interact with the FSHR that is dominantly expressed in the granulosa cells. The oral administration of LMW FSHR agonists with a short circulation time, induced formation of luteinized unruptured follicles (LUFs) from the Graafian follicles, thereby preventing the release of the oocyte. The short-acting LMW FSHR compounds were fully agonistic to FSHR (EC(50)=4-5 nM). In an isolated mouse follicle culture, a short incubation period (2 h) resulted in inhibition of follicular rupture, where continuous incubation induced follicle growth. Pharmacokinetics after oral administration showed a surge-like exposure in rats and monkeys. Oral administration of short-acting LMW FSHR agonists inhibited ovulation at 10 mg/kg in rats and guinea pigs by generating LUFs without affecting cyclicity. Also, inhibition of follicular rupture was shown to be reversible within one cycle. Finally, LUFs were induced without affecting the hormonal cyclicity in cynomolgus monkeys, a mono-ovulatory species. In healthy women LUF formation occurs naturally, with a LUF acting as corpus luteum that produces enough progesterone to ensure normal menstrual cyclicity. Together with the presented data this indicates that the innovative approach with short-acting LMW FSHR agonists could lead to oral contraception for females at the ovarian level. 相似文献
992.
P. C. Houtsma J. C. de Wit F. M. Rombouts 《International journal of food microbiology》1993,20(4):247-257
Pathogens and spoilage organisms occuring in meat products were screened in laboratory media, according to a method of Eklund (1983), in order to determine the specific inhibitory effect of lactate on growth of these microorganisms under optimum growth conditions (pH 6.5, 20°C). In general, Gram-positive bacteria were more sensitive towards lactate than Gram-negative bacteria. It was shown especially, that strains that were able to grow at water activities of 0.95 and below in the presence of NaCl (Staphylococcus aureus, Listeria monocytogenes, Brochothrix thermosphacta) were inhibited by sodium lactate (NaL). It appeared, that yeasts were resistant to large amounts of NaL (> 10% w/v). However, NaL had a specific inhibitory effect on growth of these organisms when compared to the effect of NaCl. These results indicate that lactate addition to food products with a pH near neutrality offers good prospects for shelf life prolongation. 相似文献
993.
Commercial precooked corn flour (used for Venezuelan arepa preparation) was sieved into fractions using a Ro-tap shaker. Particles 297 μm thick had the highest consistency. Particles 354 μm thick had the longest stability, their yellow color value (Hunter) was the smallest, and arepas made from them had the highest elasticity. Sedimented volumes were greater for particles 297 μm thick and coarser. Functional properties, evaluated by trained judges, were better for fractions with sizes between 297 and 420 μm. Regression analysis showed that particles between these sizes are the best suited for Venezuelan arepa preparation. 相似文献
994.
Zinc Oxide Nanoparticles: Synthesis,Antimicrobial Activity and Food Packaging Applications 总被引:2,自引:0,他引:2
Paula Judith Perez Espitia Nilda de Fátima Ferreira Soares Jane Sélia dos Reis Coimbra Nélio José de Andrade Renato Souza Cruz Eber Antonio Alves Medeiros 《Food and Bioprocess Technology》2012,5(5):1447-1464
Zinc oxide (ZnO) is an inorganic compound widely used in everyday applications. ZnO is currently listed as a generally recognized
as safe (GRAS) material by the Food and Drug Administration and is used as food additive. The advent of nanotechnology has
led the development of materials with new properties for use as antimicrobial agents. Thus, ZnO in nanoscale has shown antimicrobial
properties and potential applications in food preservation. ZnO nanoparticles have been incorporated in polymeric matrices
in order to provide antimicrobial activity to the packaging material and improve packaging properties. This review presents
the main synthesis methods of ZnO nanoparticles, principal characteristics and mechanisms of antimicrobial action as well
as the effect of their incorporation in polymeric matrices. Safety issues such as exposure routes and migration studies are
also discussed. 相似文献
995.
Ramon Díaz de León Graciela Morales Pablo Acuña Florentino Soriano 《Polymer Engineering and Science》2010,50(2):373-383
Different high impact polystyrenes were synthesized using styrene/butadiene copolymers (SB) with PS/PB composition: 30/70 and 20/80 as the precursor rubber, benzoyl peroxide (BPO) as the initiator, and ter‐dodecyl mercaptane (TDM) as the chain transfer agent. During the polymerization, several samples were taken and analyzed under different techniques to evaluate the phase inversion (PI) phenomenon. The PI was determined through transmission electron microscopy (TEM) and through dynamic oscillatory behavior, where the PI takes places when the relaxation process presents the lower value of activation energy. Finally, the Choi and Schowalter emulsion model was employed to elucidate the PI, and relevant information was revealed about the interfacial tension in the PI. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers 相似文献
996.
Valerio Choque Pilar Ramírez de la Piscina Daniel Molyneux Narcís Homs 《Catalysis Today》2010,149(3-4):248-253
The partial oxidation of methane is studied at 673–873 K over new Ru-based catalysts supported on TiO2–ZrO2 with different TiO2 content. Supports were prepared by a sol–gel method, and RuCl3 and RuNO(NO3)3 were used as ruthenium precursors to prepare the catalysts (1–2 wt% Ru). The effect of the reaction temperature on the catalytic behavior is analyzed, along with the support composition and the Ru precursor used. 相似文献
997.
Adriana Gadioli Tarone Luiz Henrique Fasolin Fabiana de Assis Perrechil Míriam Dupas Hubinger Rosiane Lopes da Cunha 《Food and Bioproducts Processing》2013,91(2):111-120
Soy protein fractions rich in β-conglycinin (7S) or glycinin (11S) were freeze dried or spray dried at temperatures of 120, 150 or 180 °C. The fractions were characterized for their particle size distribution, sorption isotherms and by scanning differential calorimetry. The gelling capacity of the protein fractions was studied at pH values of 3 and 7 using oscillatory measurements, mechanical properties and water holding capacity. The rheological measurements showed that viscous modulus (G″) predominated at low temperatures and the elastic modulus (G′) at high temperatures. At pH 3, the G′–G″ crossover occurred at lower temperatures when compared to pH 7. This behaviour was more accentuated for the 11S fractions due to its capacity to form stronger gels. An increase of drying temperature led to a displacement of the gel point to higher temperatures and decreased the elasticity modulus or gelling capacity of protein fractions. These results were confirmed by the mechanical properties, since at higher temperatures the gels were more fragile and brittle, especially when formed at pH 7. 相似文献
998.
Shigeng Li Kausick Auddy Peter Barber Tara J. Hansen Jisheng Ma Hans‐Conrad zur Loye Harry J. Ploehn 《Polymer Engineering and Science》2012,52(9):1888-1902
This study used in situ polymerization to prepare polyethylene terephthalate (PET) nanocomposites incorporating Ethoquad‐modified montmorillonite (eMMT), unmodified hectorite (HCT), or phenyl hectorite (phHCT) particles to study the impact of platelet surface chemistry and loading on thermal, mechanical, and gas barrier properties. eMMT platelets reduced the PET crystallization rate without altering the ultimate degree of crystallinity. In contrast, HCT and phHCT platelets accelerated the polymer's crystallization rate and increased its crystallinity. DMA results for thermally‐quenched samples showed that as T increased past glass transition temperature (Tg), HCT and phHCT nanocomposites (and control PET) manifested precipitous drops in G′ followed by increasing G′ due to cold crystallization; in contrast, eMMT nanocomposites had much higher G′ values around Tg. This provides direct evidence of eMMT reinforcement in thermally‐quenched eMMT nanocomposites. These results suggest that eMMT has a strong, favorable interaction with PET, possibly through Ethoquad‐PET entanglement. HCT and phHCT have a fundamentally different interaction with PET that increases crystallization rate and Tg by 11 to 17°C. Water barrier improvement in eMMT nanocomposites agrees with previously published oxygen barrier results and can be rationalized in terms of a tortuous path gas barrier model. POLYM. ENG. SCI., 52:1888–1902, 2012. © 2012 Society of Plastics Engineers 相似文献
999.
Marina A. Djadchenko Kasimir K. Pivnitsky Rainer Mahrwald Hans Schick 《Advanced Synthesis \u0026amp; Catalysis》1990,332(5):737-747
A highly diastereoselective addition of 1-heptyne to substituted cyclopentanecarbaldehydes is one of the indispensable prerequisites to the construction of the (S)-3-hydroxy-1(E)-octenyl side chain of prostaglandins by palladium(II)-catalyzed [3,3]-sigmatropic rearrangement of allylic acetates. It was found that 1-titanated 1-heptynes afford the Cram product at best with a diastereofacial selectivity of 92.5%. The corresponding lithium and magnesium compounds are less diastereoselective. 相似文献
1000.
Juliana Starling Cleiton Moreira da Silva Maria Sylvia Silva Dantas Ângelo de Fátima Rodrigo L. Oréfice 《International Journal of Adhesion and Adhesives》2011,31(7):767-774
In an attempt to enrich the world of dentistry through the development of new materials, this study proposes to synthesize and incorporate a monomer containing the N-hydroxysuccinimide (NHS) ester reactive group to a dental adhesive. As such, this study developed a simple method to obtain NHS esters by employing acrylic acid (AA) and NHS in the presence of EDC (N-ethyl-N′-(3-dimethylaminopropyl)carbodiimide), from an aprotic medium. The experimental N-acryloxysuccinimide (NSA) monomer was analyzed by infrared spectroscopy (FTIR) and nuclear magnetic resonance of hydrogen (1H NMR). This monomer was then incorporated within a prepared dental adhesive, in a 5% proportion. The modified adhesive, containing NSA, was applied to the dental surface of bovine teeth to obtain an adhesive/dentin interface in vitro. The characterization of this interface by Raman spectroscopy presented the formation of new amide bonds. Moreover, through scanning electron microscopy (SEM), it became possible to observe an intense penetration of this modified adhesive on the dental surface. Considering the outcome, it can be concluded that the synthesized NSA monomer provided a favorable condition for the dental adhesives to interact chemically with the dentin collagen fibers. 相似文献