A Quantitative Diffuse Reflectance Imaging (QDRI) System for Comprehensive Surveillance of the Morphological Landscape in Breast Tumor Margins

In an ongoing effort to address the clear clinical unmet needs surrounding breast conserving surgery (BCS), our group has developed a next-generation multiplexed optical-fiber-based tool to assess breast tumor margin status during initial surgeries. Specifically detailed in this work is the performance and clinical validation of a research-grade intra-operative tool for margin assessment based on diffuse optical spectroscopy. Previous work published by our group has illustrated the proof-of-concept generations of this device; here we incorporate a highly optimized quantitative diffuse reflectance imaging (QDRI) system utilizing a wide-field (imaging area = 17cm²) 49-channel multiplexed fiber optic probe, a custom raster-scanning imaging platform, a custom dual-channel white LED source, and an astronomy grade imaging CCD and spectrograph. The system signal to noise ratio (SNR) was found to be greater than 40dB for all channels. Optical property estimation error was found to be less than 10%, on average, over a wide range of absorption (μ_a = 0–8.9cm^-1) and scattering (μ_s’ = 7.0–9.7cm^-1) coefficients. Very low inter-channel and CCD crosstalk was observed (2% max) when used on turbid media (including breast tissue). A raster-scanning mechanism was developed to achieve sub-pixel resolution and was found to be optimally performed at an upsample factor of 8, affording 0.75mm spatially resolved diffuse reflectance images (λ = 450–600nm) of an entire margin (area = 17cm²) in 13.8 minutes (1.23cm²/min). Moreover, controlled pressure application at the probe-tissue interface afforded by the imaging platform reduces repeated scan variability, providing <1% variation across repeated scans of clinical specimens. We demonstrate the clinical utility of this device through a pilot 20-patient study of high-resolution optical parameter maps of the ratio of the β-carotene concentration to the reduced scattering coefficient. An empirical cumulative distribution function (eCDF) analysis is used to reduce optical property maps to quantitative distributions representing the morphological landscape of breast tumor margins. The optimizations presented in this work provide an avenue to rapidly survey large tissue areas on intra-operative time scales with improved sensitivity to regions of focal disease that may otherwise be overlooked.     

Oxidative stress caused by pyocyanin impairs CFTR Cl(-) transport in human bronchial epithelial cells

Pyocyanin (N-methyl-1-hydroxyphenazine), a redox-active virulence factor produced by the human pathogen Pseudomonas aeruginosa, is known to compromise mucociliary clearance. Exposure of human bronchial epithelial cells to pyocyanin increased the rate of cellular release of H(2)O(2) threefold above the endogenous H(2)O(2) production. Real-time measurements of the redox potential of the cytosolic compartment using the redox sensor roGFP1 showed that pyocyanin (100 microM) oxidized the cytosol from a resting value of -318+/-5 mV by 48.0+/-4.6 mV within 2 h; a comparable oxidation was induced by 100 microM H(2)O(2). Whereas resting Cl(-) secretion was slightly activated by pyocyanin (to 10% of maximal currents), forskolin-stimulated Cl(-) secretion was inhibited by 86%. The decline was linearly related to the cytosolic redox potential (1.8% inhibition/mV oxidation). Cystic fibrosis bronchial epithelial cells homozygous for DeltaF508 CFTR failed to secrete Cl(-) in response to pyocyanin or H(2)O(2), indicating that these oxidants specifically target the CFTR and not other Cl(-) conductances. Treatment with pyocyanin also decreased total cellular glutathione levels to 62% and cellular ATP levels to 46% after 24 h. We conclude that pyocyanin is a key factor that redox cycles in the cytosol, generates H(2)O(2), depletes glutathione and ATP, and impairs CFTR function in Pseudomonas-infected lungs.     

Structural refinement of insecticidal plant proteinase inhibitors from Nicotiana alata

Ornamental tobacco (Nicotiana alata) produces a series of 6 kDa proteinase inhibitors belonging to the potato type II inhibitor family. These proteins inhibit trypsin and chymotrypsin, the main digestive enzymes of predatory insects, thus leading to starvation, impaired larval development or death. In this context, the three-dimensional structures of these inhibitors are important for developing novel strategies for pest control. The solution structures of C1 and T1, the two main prototypes of the N. alata inhibitors, were originally determined more than a decade ago (J. Mol. Biol. 242, 231-243 (1994) and Biochemistry 34, 14304-14311 (1995)). Since then methods for NMR structure calculations have evolved considerably. Here we report the refinement of the structures of C1 and T1 with state-of-the-art protocols for NMR structure calculations. This refinement leads to an improved quality of the structures, making them a more reliable basis for the development of novel pesticides and modeling applications.     

The phytoestrogens daidzein and genistein enhance the insulin-stimulated sulfate uptake in articular chondrocytes

Clinical observations have suggested a relationship between osteoarthritis and a changed estrogen metabolism in menopausal women. Phytoestrogens have been shown to ameliorate various menopausal symptoms. Proteoglycans (PG) consisting of low and high sulfated glycosaminoglycans (GAG) are the main components of articular cartilage matrix, and their synthesis is increased by insulin in growth plate cartilage. We have investigated whether GAG synthesis and sodium [35S]sulfate incorporation in female bovine articular chondrocytes are affected by daidzein, genistein, and/or insulin. For comparative purposes, estradiol incubations were performed. Articular chondrocytes were cultured in monolayers at 5% O2 and 5% CO2 in medium containing serum for 7 days followed by the addition of 10(-11) M-10(-4) M daidzein, genistein, 17beta-estradiol, or 5 microg/ml insulin in a serum-free culture phase of 2 days. Photometrically analyzed GAG synthesis was significantly suppressed by high doses (10(-5) M-10(-4) M) of daidzein, genistein, and 17beta-estradiol. Although insulin raised the sodium [35S]sulfate uptake significantly, different concentrations of daidzein, genistein, or 17beta-estradiol showed no significant effects. However, the stimulating effect of insulin on sulfate incorporation was enhanced significantly after preincubation of cells with 10(-11) M-10(-5) M daidzein or 10(-9) M-10(-5) M genistein but not by 17beta-estradiol. In view of the risks of long-term estrogen replacement therapy, further experiments should clarify the potential benefit of phytoestrogens and insulin in articular cartilage metabolism.     

Antisense RNA Inhibition of RbcS Gene Expression Reduces Rubisco Level and Photosynthesis in the C4 Plant Flaveria bidentis

The C4 dicot Flaveria bidentis was genetically transformed with an antisense RNA construct targeted to the nuclear-encoded gene for the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; RbcS). RbcS mRNA levels in leaves of transformants were reduced by as much as 80% compared to wild-type levels, and extractable enzyme activity was reduced by up to 85%. There was no significant effect of transformation with the gene construct on levels of other photosynthetic enzymes. Antisense transformants with reduced Rubisco activity exhibited a stunted phenotype. Rates of photosynthesis were reduced in air at high light and over a range of CO2 concentrations but were unaffected at low light. From these results we conclude that, as is the case in C3 plants, Rubisco activity is a major determinant of photosynthetic flux in C4 plants under high light intensities and air levels of CO2.     

Detection of a restriction site polymorphism within the human α-globin gene complex

Summary A mutant RsaI restriction endonuclease site of high frequency has been identified in individuals of German, Greek, Italian, and Turkish origin. The mutation was found within the -globin gene complex and is located 0.7 kb 5 to the -globin gene. In individuals of central European origin 34 out of 58 chromosomes exhibited the -gene linkage to the presence of the polymorphic site, and thus a preliminary estimate of the gene frequency for this allele would be 0.59. DNA analysis data of individuals derived from Mediterranean populations indicate a distribution of this polymorphic marker in similar frequencies.     

Physiological homogeneity among the endosymbionts of Riftia pachyptila and Tevnia jerichonana revealed by proteogenomics

The two closely related deep-sea tubeworms Riftia pachyptila and Tevnia jerichonana both rely exclusively on a single species of sulfide-oxidizing endosymbiotic bacteria for their nutrition. They do, however, thrive in markedly different geochemical conditions. A detailed proteogenomic comparison of the endosymbionts coupled with an in situ characterization of the geochemical environment was performed to investigate their roles and expression profiles in the two respective hosts. The metagenomes indicated that the endosymbionts are genotypically highly homogeneous. Gene sequences coding for enzymes of selected key metabolic functions were found to be 99.9% identical. On the proteomic level, the symbionts showed very consistent metabolic profiles, despite distinctly different geochemical conditions at the plume level of the respective hosts. Only a few minor variations were observed in the expression of symbiont enzymes involved in sulfur metabolism, carbon fixation and in the response to oxidative stress. Although these changes correspond to the prevailing environmental situation experienced by each host, our data strongly suggest that the two tubeworm species are able to effectively attenuate differences in habitat conditions, and thus to provide their symbionts with similar micro-environments.