Photostability of quantum dots with amphiphilic polymer-based passivation strategies.

Quantum dots (QDs) have many appealing properties for biological fluorescence imaging, but exhibit photostabilities that are dependent upon surface passivation to minimize susceptibility to oxygen and light. Here, through spectroscopy and imaging techniques, we compare the photostability of micelle-encapsulated QDs with QDs passivated with either crosslinked amphiphilic polymers or crosslink-free amphiphilic polymers. Both crosslinked and crosslink-free amphiphilic polymer passivation strategies produced QDs with high photoluminescence stability for exposure to light under ambient conditions. In contrast, micelle encapsulation resulted in QDs with photoluminescence emission levels that were highly sensitive to both light exposure and oxygen, exhibiting a reduction of up to 70% in photoluminescence intensity within twenty minutes of exposure. With the addition of reducing agents, the photoluminescence level of the micelle-encapsulated QDs was significantly stabilized. We conclude that amphiphilic polymers provide coatings with considerably higher integrity and stability than micelle encapsulation, reducing the QDs' sensitivities to oxygen and light, both of which are relevant factors in biological imaging applications.

[Masticatory pain-dysfunction syndrome apropos of 60 cases]. / Syndrome algo-fonctionnel de l'appareil manducateur (SADAM) a propos de 60 cas.

Costen syndroma or temporo-mandibular joint disorders is not welknow in the ENT service, despite the common presentation with otalgia. We therefore present 60 cases diagnose in our hospital and present clinical and therapeutic aspect.

Optical systems for in vivo molecular imaging of cancer.

Progress toward a molecular characterization of cancer would have important clinical benefits; thus, there is an important need to image the molecular features of cancer in vivo. In this paper, we describe a comprehensive strategy to develop inexpensive, rugged and portable optical imaging systems for molecular imaging of cancer, which couples the development of optically active contrast agents with advances in functional genomics of cancer. We describe initial results obtained using optically active contrast agents to image the expression of three well known molecular signatures of neoplasia: including over expression of the epidermal growth factor receptor (EGFR), matrix metallo-proteases (MMPs), and oncoproteins associated with human papillomavirus (HPV) infection. At the same time, we are developing inexpensive, portable optical systems to image the morphologic and molecular signatures of neoplasia noninvasively in real time. These real-time, portable, inexpensive systems can provide tools to characterize the molecular features of cancer in vivo.

The composition of glyphosate-tolerant soybean seeds is equivalent to that of conventional soybeans.

One important aspect of the safety assessment of genetically engineered crops destined for food and feed uses is the characterization of the consumed portion of the crop. One crop currently under development, glyphosate-tolerant soybeans (GTS), was modified by the addition of a glyphosate-tolerance gene to a commercial soybean cultivar. The composition of seeds and selected processing fractions from two GTS lines, designated 40-3-2 and 61-67-1, was compared with that of the parental soybean cultivar, A5403. Nutrients measured in the soybean seeds included macronutrients by proximate analyses (protein, fat, fiber, ash, carbohydrates), amino acids and fatty acids. Antinutrients measured in either the seed or toasted meal were trypsin inhibitor, lectins, isoflavones, stachyose, raffinose and phytate. Proximate analyses were also performed on batches of defatted toasted meal, defatted nontoasted meal, protein isolate, and protein concentrate prepared from GTS and control soybean seeds. In addition, refined, bleached, deodorized oil was made, along with crude soybean lecithin, from GTS and control soybeans. The analytical results demonstrated the GTS lines are equivalent to the parental, conventional soybean cultivar.

The expressed protein in glyphosate-tolerant soybean, 5-enolpyruvylshikimate-3-phosphate synthase from Agrobacterium sp. strain CP4, is rapidly digested in vitro and is not toxic to acutely gavaged mice.

The safety of 5-enolpyruvylshikimate-3-phosphate synthase enzyme derived from Agrobacterium sp. strain CP4 (CP4 EPSPS) was assessed. CP4 EPSPS is the only protein introduced by genetic manipulation that is expressed in glyphosate-tolerant soybeans, which are being developed to provide new weed-control options for farmers. Expression of this protein in plants imparts high levels of glyphosate tolerance. The safety of CP4 EPSPS was ascertained by evaluating both physical and functional characteristics. CP4 EPSPS degrades readily in simulated gastric and intestinal fluids, suggesting that this protein will be degraded in the mammalian digestive tract upon ingestion as a component of food or feed, There were no deleterious effects due to the acute administration of CP4 EPSPS to mice by gavage at a high dosage of 572 mg/kg body wt, which exceeds 1000-fold tha anticipated consumption level of food products potentially containing CP4 EPSPS protein. CP4 EPSPS does not pose any important allergen concerns because this protein does not possess characteristics typical of allergenic proteins. These data, in combination with seed compositional analysis and animal feeding studies, support the conclusion that glyphosate-tolerant soybean are as safe and nutritious as traditional soybeans currently being marketed.

Expression of cowpea mosaic virus coat protein precursor in transgenic tobacco plants.

Tobacco, Nicotiana tabacum L., supports cowpea mosaic virus (CPMV) replication and cell-to-cell movement, and thus may serve as a model system to study coat protein-mediated protection against CPMV. A chimeric gene consisting of the cauliflower mosaic virus 35S promoter, CPMV 60K coat proteins-precursor (CP-P) coding region, and the nopaline synthase polyadenylation signal was transferred to tobacco cv. Burley 21 via the Agrobacterium tumefaciens binary vector system. Gene integration and expression in the transgenic tobacco plants were confirmed by Southern and RNA dot blot analyses. Accumulation of CPMV 60K CP-P in transgenic plants, up to 2 micrograms/g of wet weight tissue, was detected by ELISA and Western blots. The results of Western blots and immunosorbent electron microscopy further indicated that CPMV CP-P neither undergoes autoproteolysis to generate the mature viral coat proteins nor assembles into virus-like capsids, suggesting that processing of the CP-P may be required for virus assembly. Because CPMV neither induces symptoms in tobacco nor moves systemically, evaluation of the reactions of the transgenic plants to virus inoculation was based on virus accumulation in the inoculated leaves. Results from such infectivity experiments did not differentiate between CP-P expressers and vector-transformed plants. The transgenic tobacco plants expressing CP-P should provide valuable material for investigating comovirus polyprotein processing and capsid assembly in vivo.

[Experimental study of variations of salivary pH affected by chewing cola]. / Etude expérimentale des variations du pH salivaire sous l'influence de la mastication de la kola.

Study on the theory that cola-chewing affects dental decays by changing pH in saliva shows--a short term increase in saliva pH (approx. 1.02) becoming normal again after 30 minutes. Spacing cola consumption out during the day and after meals rich in carbohydrates can compensate for the drop in saliva pH. The change in saliva pH is one of the factors which reduces dental decay in people who chew cola.

Resistance of Drosophila to cadmium: biochemical factors in resistant and sensitive strains.

With regard to cadmium toxicity, Drosophila strains v;bw and Austin represent extremes in resistance and sensitivity, respectively. Both strains produced metallothionein (MT) in response to Cd ions in their diet. Austin produced more metallothionein than v;bw at Cd ion levels below 0.2 mM, when both strains were allowed lifetime development on Cd2+-containing media. When the rate of MT appearance was measured for 4 days in young adults the results showed no clear trend with time within a strain or between strains. The plot of LC50 vs. MT levels for identical developmental conditions revealed that for v;bw small increases in MT corresponded to large increases in resistance whereas for the sensitive Austin even large increases in MT had comparatively little effect on increasing LC50. Results given here suggest that differences in total MT content do not explain the genetically demonstrable difference in Cd2+-resistance between v;bw and Austin. However, since two MT genes are identified in Drosophila, differences in resistance could be reflective of greater relative amounts of one "more important" MT in the resistant fly.