Body temperature in premature infants during the first week of life: Exploration using infrared thermal imaging.

BACKGROUND: Hypothermia is a problem for very premature infants after birth and leads to increased morbidity and mortality. Previously we found very premature infants exhibit abnormal thermal patterns, keeping foot temperatures warmer than abdominal temperatures for their first 12h of life. PURPOSE: We explored the utility of infrared thermography as a non-invasive method for measuring body temperature in premature infants in an attempt to regionally examine differential temperatures. RESULTS: Our use of infrared imaging to measure abdominal and foot temperature for extremely premature infants in heated, humid incubators was successful and in close agreement using Bland and Altman technique with temperatures measured by skin thermistors. CONCLUSIONS: Our study methods demonstrated that it was feasible to capture full body temperatures of extremely premature infants while they were resting in a heated, humid incubator using a Flir SC640 infrared camera. This technology offers researchers and clinicians a method to examine acute changes in perfusion differentials in premature infants which may lead to morbidity.

Mechanism of adhesion maintenance by methionine sulphoxide reductase in Streptococcus gordonii.

Methionine sulphoxide reductase maintains adhesin function during oxidative stress. Using Streptococcus gordonii as a model, we now show the mechanistic basis of adhesin maintenance provided by MsrA. In biofilms, S. gordonii selectively expresses the msrA gene. When the wild-type strain was grown with exogenous hydrogen peroxide (H(2)O(2)), msrA-specific mRNA expression significantly increased, while acid production was unaffected. In the presence of H(2)O(2), a msrA-deletion mutant (ΔMsrA) showed a 6 h delay in lag phase growth, a 30% lower yield of H(2)O(2), significantly greater inhibition by H(2)O(2) on agar plates (reversed by complementation), 30% less adhesion to saliva-coated hydroxyapatite, 87% less biofilm formation and an altered electrophoretic pattern of SspAB protein adhesins. Using mass spectrometry, methionine residues in the Met-rich central region of SspB were shown to be oxidized by H(2)O(2) and reduced by MsrA. In intact wild-type cells, MsrA colocalized with a cell wall-staining dye, and MsrA was detected in both cell wall and cytosolic fractions. To maintain normal adhesion and biofilm function of S. gordonii in response to exogenous oxidants therefore msrA is upregulated, methionine oxidation of adhesins and perhaps other proteins is reversed, and adhesion and biofilm formation is maintained.

Infrared imaging of trauma patients for detection of acute compartment syndrome of the leg.

OBJECTIVE: Early compartment syndrome is difficult to diagnose, and a delay in the diagnosis can result in amputation or death. Our objective was to explore the potential of infrared imaging, a portable and noninvasive technology, for detecting compartment syndrome in the legs of patients with multiple trauma. We hypothesized that development of compartment syndrome is associated with a reduction in surface temperature in the involved leg and that the temperature reduction can be detected by infrared imaging. DESIGN: Observational clinical study. SETTING: Level I trauma center between July 2006 and July 2007. PATIENTS: Trauma patients presenting to the emergency department. INTERVENTIONS: Average temperature of the anterior surface of the proximal and distal region of each leg was measured in the emergency department with a radiometrically calibrated, 320 x 240, uncooled microbolometer infrared camera. MEASUREMENTS AND MAIN RESULTS: The difference in surface temperature between the thigh and foot regions (thigh-foot index) of the legs in trauma patients was determined by investigators blinded to injury pattern using thermographic image analysis software. The diagnosis of compartment syndrome was made intraoperatively. Thermographic images from 164 patients were analyzed. Eleven patients developed compartment syndrome, and four of those patients had bilateral compartment syndrome. Legs that developed compartment syndrome had a greater difference in proximal vs. distal surface temperature (8.80 +/- 2.05 degrees C) vs. legs without compartment syndrome (1.22 +/- 0.88 degrees C) (analysis of variance p < .01). Patients who developed unilateral compartment syndrome had a greater proximal vs. distal temperature difference in the leg with (8.57 +/- 2.37 degrees C) vs. the contralateral leg without (1.80 +/- 1.60 degrees C) development of compartment syndrome (analysis of variance p < .01). CONCLUSIONS: Infrared imaging detected a difference in surface temperature between the proximal and distal leg of patients who developed compartment syndrome. This technology holds promise as a supportive tool for the early detection of acute compartment syndrome in trauma patients.

Longwave infrared (LWIR) coded aperture dispersive spectrometer.

We describe a static aperture-coded, dispersive longwave infrared (LWIR) spectrometer that uses a microbolometer array at the detector plane. The two-dimensional aperture code is based on a row-doubled Hadamard mask with transmissive and opaque openings. The independent column code nature of the matrix makes for a mathematically well-defined pattern that spatially and spectrally maps the source information to the detector plane. Post-processing techniques on the data provide spectral estimates of the source. Comparative experimental results between a slit and coded aperture for emission spectroscopy from a CO(2) laser are demonstrated.

Preliminary crystallographic analysis of trypanothione reductase from Crithidia fasciculata.

Trypanothione reductase, a flavoprotein disulfide reductase specific to trypanosomatid parasites, has been crystallized by vapor diffusion of a protein solution (10 mg/ml) against 22% polyethylene glycol (average Mr 8000) containing 100 mM-ammonium sulfate. Crystals of a size suitable for structure determination by X-ray diffraction have been obtained by seeding protein solutions with smaller crystals. The space-group is P21 (a = 60.9 A, b = 161.8 A, c = 58.4 A, beta = 99.1 degrees). The molecular mass and volume of the unit cell suggest that there is a dimer of the enzyme in the asymmetric unit, and this is confirmed by self-rotation functions calculated using data to 4.5 A resolution. The crystals diffract to beyond 3 A resolution. Crystals of another P21 form (a = 91.3 A, b = 114.4 A, c = 92.0 A, beta = 141.3 degrees) are observed to grow under similar conditions.

Nolinear optical liquid cored fiber array and liquid crystal film fo ps-cw frequency agile laser optical limiting application.

The molecular nonlinear photonic absorption processes of two nonlinear fiber core liquids are discussed in the context of nonlinear propagation and optical limiting of short pulses. These fiber arrays are capable of limiting threshold and clamped output below 1 micro J for picosecond and nanosecond pulses. We also discuss the observation of perhaps the largest optical nonlinearity in some dye-doped nematic liquid crystal films. These films will provide limiting action with a threshold power of 100 nWatt and limited transmission of << 1 microJoule for ms - cw laser.

IL-1 receptor regulates S100A8/A9-dependent keratinocyte resistance to bacterial invasion.

Previously, we reported that epithelial cells respond to exogenous interleukin (IL)-1α by increasing expression of several genes involved in the host response to microbes, including the antimicrobial protein complex calprotectin (S100A8/A9). Given that S100A8/A9 protects epithelial cells against invading bacteria, we studied whether IL-1α augments S100A8/A9-dependent resistance to bacterial invasion of oral keratinocytes. When inoculated with Listeria monocytogenes, human buccal epithelial (TR146) cells expressed and released IL-1α. Subsequently, IL-1α-containing media from Listeria-infected cells increased S100A8/A9 gene expression in naïve TR146 cells an IL-1 receptor (IL-1R)-dependent manner. Incubation with exogenous IL-1α decreased Listeria invasion into TR146 cells, whereas invasion increased with IL-1R antagonist. Conversely, when S100A8/A9 genes were knocked down using short hairpin RNA (shRNA), TR146 cells responded to exogenous IL-1α with increased intracellular bacteria. These data strongly suggest that infected epithelial cells release IL-1α to signal neighboring keratinocytes in a paracrine manner, promoting S100A8/A9-dependent resistance to invasive L. monocytogenes.

Cross-correlation discrimination for optical cavity modes.

Matched spatial filters were constructed for various modes of a spherical Fabry-Perot interferometer (FPSI). The cross correlation between many of these modes was obtained experimentally as well as theoretically. The orthogonality between various modes was demonstrated and used in order to discriminate against all orthogonal modes. A discrimination funtion that predicts the performance of the matched-filtering process is defined and analytically evaluated for rectangular and cylindrical Gaussian modes. It is shown that arbitrary discrimination strength can be obtained at the sacrifice of output signal strength. It was experimentally demonstrated that a scanning FPSI used in conjunction with only one zero-order-mode filter could be used over nearly its entire domain of stable cavity spacings and still maintain a full (c/2L) free spectral range.

Optical transducer for reception of ultrasonic waves.

A new optical transducer for the detection of acoustic pressure in the diagnostic ultrasound frequency range is described. This transducer is based on the modulation of an evanescent light field by the incident acoustic energy. Theoretical design considerations are presented for the purpose of developing the most sensitive transducer. Based on these considerations an experimental transducer was constructed. Although less sensitive than predicted this device was capable of transducing ultrasonic pulses with a 1.0-MHz center frequency at diagnostic ultrasound amplitude levels. The techniques developed here are applicable for two-dimensional transduction and may prove a viable alternative to piezoelectric array transducers.

Role of photodetectors in optical signal processing.

Optical signal processing applications place demands on photodetector arrays beyond those encountered in image sensing applications. We review the basic requirements and show that increased dynamic range and nonlinear decision operations that lead to reduced output data rates are the key improvements needed for both 1-and 2-D arrays. Arrays of high-speed photodetector elements with integrated postdetection circuitry are also needed. Although we suggest some possible methods for achieving these goals, our main objective is to stimulate the photodetector community to design and fabricate more useful devices.

Nonlinear liquid-crystal fiber structures for passive optical limiting of short laser pulses.

Optical limiting of nanosecond and picosecond laser pulses through millimeter-length isotropic liquid-crystalcored fiber structures is reported. Low limiting threshold and clamped transmitted outputs are observed. The underlying nonlinear mechanisms are nonlinear photoabsorptions and scattering and lossy waveguiding caused by laser-induced thermal-density index fluctuations.

Coherent beam amplification with a photorefractive liquid crystal.

Coherent amplification of a signal beam by a strong pump beam is observed in thin films of fullerene-doped nematic liquid crystal. Exponential gain constants as high as 2890 cm(-1) with no phase cross talk are achieved at low applied dc bias voltage and pump beam intensity. The underlying mechanism is the electro-optically induced spatially reorientation of the liquid-crystal axis and the resultant phase-shifted index grating required for two-beam coupling.

The structure and properties of methylenetetrahydrofolate reductase from Escherichia coli suggest how folate ameliorates human hyperhomocysteinemia.

Elevated plasma homocysteine levels are associated with increased risk for cardiovascular disease and neural tube defects in humans. Folate treatment decreases homocysteine levels and dramatically reduces the incidence of neural tube defects. The flavoprotein methylenetetrahydrofolate reductase (MTHFR) is a likely target for these actions of folate. The most common genetic cause of mildly elevated plasma homocysteine in humans is the MTHFR polymorphism A222V (base change C677-->T). The X-ray analysis of E. coli MTHFR, reported here, provides a model for the catalytic domain that is shared by all MTHFRs. This domain is a beta8alpha8 barrel that binds FAD in a novel fashion. Ala 177, corresponding to Ala 222 in human MTHFR, is near the bottom of the barrel and distant from the FAD. The mutation A177V does not affect Km or k(cat) but instead increases the propensity for bacterial MTHFR to lose its essential flavin cofactor. Folate derivatives protect wild-type and mutant E. coli enzymes against flavin loss, and protect human MTHFR and the A222V mutant against thermal inactivation, suggesting a mechanism by which folate treatment reduces homocysteine levels.

Optically induced space-charge fields, dc voltage, and extraordinarily large nonlinearity in dye-doped nematic liquid crystals.

We have observed extraordinarily large optical nonlinearity in Methyl Red-doped nematic liquid-crystal film. Grating diffraction can be generated with an optical intensity as low as 40 microW/cm(2) , and a refractive-index change coefficient of more than 6 cm(2)/ W is obtained. The effect is attributed to formation of an optically induced dc space-charge field and to the resulting reorientation of the highly birefringent nematic director axis.