Micro- and nano-patterned conductive graphene-PEG hybrid scaffolds for cardiac tissue engineering.

A lack of electrical conductivity and structural organization in currently available biomaterial scaffolds limits their utility for generating physiologically representative models of functional cardiac tissue. Here we report on the development of scalable, graphene-functionalized topographies with anisotropic electrical conductivity for engineering the structural and functional phenotypes of macroscopic cardiac tissue constructs. Guided by anisotropic electroconductive and topographic cues, the tissue constructs displayed structural property enhancement in myofibrils and sarcomeres, and exhibited significant increases in the expression of cell-cell coupling and calcium handling proteins, as well as in action potential duration and peak calcium release.

Contraction-Induced Changes in Hydrogen Bonding of Muscle Hydration Water.

Protein-water interaction plays a crucial role in protein dynamics and hence function. To study the chemical environment of water and proteins with high spatial resolution, synchrotron radiation-Fourier transform infrared (SR-FTIR) spectromicroscopy was used to probe skeletal muscle myofibrils. Observing the OH stretch band showed that water inside of relaxed myofibrils is extensively hydrogen-bonded with little or no free OH. In higher-resolution measurements obtained with single isolated myofibrils, the water absorption peaks were relatively higher within the center region of the sarcomere compared to those in the I-band region, implying higher hydration capacity of thick filaments compared to the thin filaments. When specimens were activated, changes in the OH stretch band showed significant dehydrogen bonding of muscle water; this was indicated by increased absorption at ∼3480 cm-1 compared to relaxed myofibrils. These contraction-induced changes in water were accompanied by splitting of the amide I (C=O) peak, implying that muscle proteins transition from α-helix to ß-sheet-rich structures. Hence, muscle contraction can be characterized by a loss of order in the muscle-protein complex, accompanied by a destructuring of hydration water. The findings shed fresh light on the molecular mechanism of muscle contraction and motor protein dynamics.

Impact of Hydrophilic Surfaces on Interfacial Water Dynamics Probed with NMR Spectroscopy.

In suspensions of Nafion beads and of cationic gel beads, NMR spectroscopy showed two water-proton resonances, one representing intimate water layers next to the polymer surface, the other corresponding to water lying beyond. Both resonances show notably shorter spin-lattice relaxation times (T1) and smaller self-diffusion coefficients (D) indicating slower dynamics than bulk water. These findings confirm the existence of highly restricted water layers adsorbed onto hydrophilic surfaces and dynamically stable water beyond the first hydration layers. Thus, aqueous regions on the order of micrometers are dynamically different from bulk water.

Effect of radiant energy on near-surface water.

While recent research on interfacial water has focused mainly on the few interfacial layers adjacent to the solid boundary, century-old studies have extensively shown that macroscopic domains of liquids near interfaces acquire features different from the bulk. Interest in these long-range effects has been rekindled by recent observations showing that colloidal and molecular solutes are excluded from extensive regions next to many hydrophilic surfaces [Zheng and Pollack Phys. Rev. E 2003, 68, 031408]. Studies of these aqueous "exclusion zones" reveal a more ordered phase than bulk water, with local charge separation between the exclusion zones and the regions beyond [Zheng et al. Colloid Interface Sci. 2006, 127, 19; Zheng and Pollack Water and the Cell: Solute exclusion and potential distribution near hydrophilic surfaces; Springer: Netherlands, 2006; pp 165-174], here confirmed using pH measurements. The main question, however, is where the energy for building these charged, low-entropy zones might come from. It is shown that radiant energy profoundly expands these zones in a reversible, wavelength-dependent manner. It appears that incident radiant energy may be stored in the water as entropy loss and charge separation.

Role of proton gradients in the mechanism of osmosis.

Experiments were carried out to determine whether the newly identified "exclusion zone" found adjacent to hydrophilic surfaces might play a role in osmosis. Two chambers were juxtaposed face to face, separated by a membrane made of cellulose acetate or Nafion. One chamber contained water, the other 100 mM sodium sulfate solution. Osmotically driven transmembrane fluid flow from low to high salt was observed using both membranes, in agreement with previous reports. Characteristic pH differences and potential differences between chambers were also noted. Visual examination with microsphere markers revealed extensive exclusion zones adjacent to both types of membrane. As these zones routinely generate protons in the water regions beyond, unequal proton concentrations in the respective chambers may be responsible for creating both the pH and potential gradients, which may be ultimately responsible for the osmotic drive.

Utility of an informational intranet in a radiology department.

RATIONALE AND OBJECTIVES: The authors performed this study to assess the usefulness of the various features of their radiology department intranet and to quantify its effect in facilitating intradepartmental information flow. MATERIALS AND METHODS: The number, length, and nature of visits to each directory on the intranet were recorded by a commercially available intranet analysis software package. RESULTS: During the last 6 months of 2001, 89,411 page views (mean, 485 per day) occurred during 26,344 visits to the radiology department intranet. The most commonly accessed features were billing code lists (29% of total views); the intranet home page (27%); faculty telephone and pager numbers (2.6%); digital dictation access codes (1.6%); and magnetic resonance imaging protocols (1.5%). A total of 32,408 files, including daily clinical assignments, monthly fellow and resident schedules, and protocol forms, were downloaded as portable document files by intranet users. CONCLUSION: The intranet has proved an invaluable addition to the authors' departmental infrastructure, as evidenced by its extensive use by the staff. It has facilitated the rapid dissemination of information without hard copy.

Is there an increased incidence of contralateral testicular cancer in patients with intratesticular microlithiasis?

OBJECTIVE: The objective of this study was to determine if there is an association between intratesticular microlithiasis and contralateral testicular cancer. MATERIALS AND METHODS: Retrospective review of a radiology database revealed 156 men who had undergone testicular sonography and orchiectomy for testicular cancer. Sonographic abnormalities were correlated with medical records and histopathology. Statistical significance was assessed using Fisher's exact test. RESULTS: Twenty-three (15%) of 156 patients with prior orchiectomy for testicular cancer had microlithiasis, and 133 (85%) did not have microlithiasis. Four of 23 patients with microlithiasis had masses, and eight had heterogeneous changes. Sonograms of 133 patients without microlithiasis revealed masses in seven and heterogeneous changes in 15 patients. Five patients with microlithiasis and six without microlithiasis underwent a second orchiectomy. Contralateral testicular cancer was confirmed in five (22%) of 23 patients with microlithiasis versus three (2%) of 133 men without microlithiasis. Microlithiasis was present in five (63%) of eight patients with bilateral testicular cancer, and microlithiasis was highly associated with confirmed bilateral testicular cancer (5/23 vs 3/133, odds ratio [OR] = 12.0, p = 0.002). Among the 34 patients who had either testicular masses or heterogeneous changes, microlithiasis had an OR of 4.5 (p = 0.10). CONCLUSION: In our study, contralateral testicular cancer was significantly associated with intratesticular microlithiasis. Nevertheless, there was not sufficient evidence that intratesticular microlithiasis adds independent diagnostic information for bilateral testicular cancer in the absence of a mass or heterogeneous changes.