Definition, risk factors and outcome of prolonged surgical intensive care unit stay

There is no generally accepted definition for a "prolonged surgical intensive care unit (SICU) stay". The aims of the current study were to: (1) define prolonged SICU stay; (2) identify risk factors of prolonged SICU stay; and (3) identify risk factors of hospital mortality in patients with a prolonged SICU stay. All SICU patients aged >16 years and with an intensive care unit (ICU) stay longer than three days without ICU readmission between 1 January 2004 and 30 November 2006 at the National Taiwan University Hospital were recruited to the study. A total of 2598 patients were recruited. ICU stay >16 days was defined as a prolonged SICU stay since rates of ICU mortality, hospital mortality and mortality one year after ICU discharge remained stationary after ICU stay was >16 days. A multivariate logistic regression model identified factors associated with a prolonged SICU stay, including age more than 70 years old, (odds ratio 1.587, 95% confidence interval 1.246 to 2.022), increasing pre-ICU hospital days (odds ratio 1.009, 95% confidence interval 1.003 to 1.015), admission from emergency (odds ratio 1.925, 95% confidence interval 1.455 to 2.548), use of mechanical circulation support (odds ratio 2.314, 95% confidence interval 1.458 to 3.674) and renal replacement therapy (odds ratio 5.140, 95% confidence interval 3.781 to 6.987). A multivariate logistic regression model identified factors associated with ICU mortality in patients with ICU stay >16 days, including renal replacement therapy (odds ratio 4.780, 95% confidence interval 2.687 to 8.504). An ICU stay >16 days could be used to define prolonged SICU stay when hospital and one-year mortality rates are considered. Prevention of organ failure requiring renal replacement therapy might prove a useful goal to avoid prolonged ICU stay and even hospital mortality.

Notch signaling and developmental cell-cycle arrest in Drosophila polar follicle cells

Temporal and spatial regulation of cell division is critical for proper development of multicellular organisms. An important aspect of this regulation is cell-cycle arrest, which in many cell types is coupled with differentiated status. Here we report that the polar cells--a group of follicle cells differentiated early during Drosophila oogenesis--are arrested at G2 phase and can serve as a model cell type for investigation of developmental regulation of cell-cycle arrest. On examining the effects of String, a mitosis-promoting phosphatase Cdc25 homolog, and Notch signaling in polar cells, we found that misexpression of String can trigger mitosis in existing polar cells to induce extra polar cells. Normally, differentiation of the polar cells requires Notch signaling. We found that the Notch-induced extra polar cells arise through recruitment of the neighboring cells rather than promotion of proliferation, and they are also arrested at G2 phase. Notch signaling is probably involved in down-regulating String in polar cells, thus inducing the G2 cell-cycle arrest.

Loop-mediated isothermal amplification method for rapid detection of Vibrio alginolyticus, the causative agent of vibriosis in mariculture fish

AIMS

The purpose of this study was to develop a loop-mediated isothermal amplification (LAMP) method for the rapid, sensitive and simple detection of Vibrio alginolyticus in mariculture fish.

METHODS AND RESULTS

LAMP primers were designed by targeting the gyrB gene. With Bst DNA polymerase, the target DNA can be clearly amplified for 60 min at 64 degrees C in a simple water bath. The detection sensitivity of the LAMP assay for the detection of V. alginolyticus is about 3.7 x 10(2) CFU ml(-1) (3.7 CFU per reaction). LAMP products could be judged with agar gel or naked eye after the addition of SYBR Green I. There were no cross-reactions with other bacterial strains indicating a high specificity of the LAMP. The LAMP method was applied to detect V. alginolyticus-infected fish tissues effectively.

CONCLUSIONS

The LAMP established in this study is a simple, sensitive, specific, inexpensive and rapid protocol for the detection of V. alginolyticus.

SIGNIFICANCE AND IMPACT OF THE STUDY

This LAMP method provides an important diagnostic tool for the detection of V. alginolyticus infection both in the laboratory and field.

Fiber-laser-pumped CW OPO for red, green, blue laser generation

We report a CW, watt-level, red, green, and blue (RGB) laser pumped by an economical multimode (1-nm linewidth) Yb-fiber laser at 1.064 mum. A singly resonant optical parametric oscillator at 1.56 mum has two intracavity sum-frequency generators for red and blue laser generation. An extracavity second harmonic generator converts the residual pump power into green laser radiation. At 25-W pump power, the laser generated 3.9, 0.456, and 0.49 W at 633, 532, and 450 nm, respectively. The multimode pump laser offers a large temperature bandwidth for operating the RGB OPO without the need of a precision crystal temperature stabilizer.

Thermal waveguide OPO

We report a mid-infrared, CW singly resonant optical parametric oscillator (OPO) with a thermally induced waveguide in its gain crystal. We measured a numerical aperture of 0.0062 for the waveguide at 80-W intracavity power at 3.2 microm. This thermal-guiding effect benefits to the stable operation of an OPO and improves the parametric conversion efficiency by more than a factor of two when compared with that without thermal guiding.

Canine CXCL7 and its functional expression in dendritic cells undergoing maturation

Many cells, including leucocytes and stromal cells, express CXCL7, a member of the CXC chemokine family, also known as platelet basic protein. CXCL7 is a potent chemoattractant and activator of neutrophil function. Dendritic cells (DCs) play a pivotal role in antigen processing and presentation. Very little information is available on the ability of DCs to recruit neutrophils by producing chemokines. In this work, we have cloned canine CXCL7. Based on the predicted gene sequence and using the 3'RACE technique, the full-length gene was amplified from LPS-treated canine peripheral blood mononuclear cells. The cloned cDNA sequence consisted of 357 nucleotides and encoded a 118 amino acid protein, including a 38 amino acid signal peptide. The use of CXCL7-containing supernatants from CXCL7-transfected BALB/3T3 in the neutrophil migration assay confirmed that canine CXCL7 had chemoattractive activity for neutrophils. We then used canine monocyte-derived DCs to generate CXCL7 for the rest of the experiment. Expression of CXCL7 by DCs treated with LPS, IL-1beta, IL-6, TGF-beta, TNF-alpha, or IFN-gamma was compared using real-time RT-PCR and Western blotting. When treated with IL-1beta, IL-6, TNF-alpha, or TGF-beta, canine DCs expressed significantly higher levels of CXCL7 mRNA and protein than when treated with IFN-gamma or LPS. It is concluded that dog DCs express high levels of the neutrophil chemotactic factor CXCL7 when stimulated by proinflammatory cytokines, including IL-1beta, IL-6, TNF-alpha, or TGF-beta, and may play an important role in modulating inflammatory responses.

Canine CD8 T cells showing NK cytotoxic activity express mRNAs for NK cell-associated surface molecules

Natural killer (NK) cells have been considered to be a group of lymphocytes lacking clonally distributed receptors for antigens typical of T cells and B cells. In some mammalian species, including humans, a subpopulation of CD8(+) peripheral blood lymphocytes (PBLs) exhibits NK activity. This NK subpopulation has not been well characterized in mammals and its characterization is particularly poor in the dog. In this study, we demonstrated that a subset of canine CD8(+) cells derived from PBLs and lymphokine (IL-2)-activated killers (LAKs) of PBLs that was CD3(+), CD4(-), CD21(-), CD5(lo), alpha/betaTCR(+), and gamma/deltaTCR(-) contained substantially higher levels of mRNAs for NK cell-related receptors (NKp30, NKp44, NKG2D, 2B4, and CD16 for PBL, and NKG2D and CD56 for LAK) than the corresponding CD8(-) cells. This subset of CD8(+) lymphocytes derived from LAKs also displayed significantly higher NK cytotoxic activity than the corresponding CD8(-) cells. In contrast, CD8(+) cells derived from nonstimulated PBLs showed very low levels of NK cytotoxic activity. Our results indicate that, in IL-2-stimulated PBLs, canine CD8(+) cells are an important subset associated with NK cytotoxic activity.

LESS NO PRODUCTION AND BETTER MOTION PARAMETER IN HUMAN SPERM BY SWIM-UP PROCESSING

Fifteen semen specimens were obtained from men for semen analysis; each was divided into two aliquots for prepararation. The motile sperm recovery rate, percentage motility, and motion parameters were measured for each semen specimen (n = 15) before and after preparation with the use of the two methods, and cultured with different time courses (1 hr, 3 hr, and 6 hr). Nitric oxide (NO) was measured using the chemiluminscence method after centrifugation. Recovery rate of motile cell was significantly higher in direct swim-up method (69.5 +/- 42.4% versus 49.3 +/- 29.3%, p < 0.05). In motility, direct swim-up method in the different time courses was significantly better than IxaPrep method. (1 hr: 91.1 +/- 5.2% vs 65.6 +/- 16.4%, 3 hr: 87.2 +/- 7.9% vs 65.2 +/- 16.5%, 6 hr: 86.1 +/- 7.5% vs 60.8 +/- 17.6% and prewash: 61.6 +/- 16.2%, p < 0.05). In VAP and VSL, the sperm prepared by the above two methods all improved compared to pre-wash sperm (p < 0.05), but there was no statistical significance between the two methods. NO production in the direct swim-up group was significantly lower than IxaPrep group in the first hour of culture (0.09 +/- 0.09 uM vs 0.15 +/- 0.09 uM, p < 0.05). NO production increased as the culture time increased in swim-up group, but conversed in IxaPrep group. The lower level of NO produced in the swim-up group may suggest that better sperm quality achieved is due to the decreased NO production.

Observation of thermal-induced optical guiding and bistability in a mid-IR continuous-wave, singly resonant optical parametric oscillator

We report the observation of thermal-induced optical guiding and bistability in a mid-IR cw, singly resonant optical parametric oscillator (SRO) at approximately 3.2 microm. The SRO employs a MgO:PPLN crystal as the gain medium and a 1-nm-linewidth Yb-fiber laser at 1.064 microm as the pump source. As soon as the pump power reaches the thermal guiding threshold at 16.5 W, the SRO shows a step increase in the parametric efficiency by a factor of 2.5. At 25 W pump power, the SRO generated 5.3 and 1.2 W at 1.58 and 3.23 microm, respectively, with single-longitudinal-mode performance for the 3.23 microm radiation.

Low-threshold, narrow-line THz-wave parametric oscillator with an intra-cavity grazing-incidence grating

We report a low-threshold, narrow-line THz-wave parametric oscillator with an intra-cavity grazing-incidence grating and a 1-mm thick, 45-mm long lithium-niobate planar waveguide. When pumped by an actively Q-switched Nd:YAG laser, the threshold energy and intensity of the parametric oscillator were about 2.2 mJ and 70 MW/cm(2), respectively. The linewidths of the output THz wave were 12 and 134 GHz with and without the intra-cavity grating, respectively.

CD5-low expression lymphocytes in canine peripheral blood show characteristics of natural killer cells

NK cell markers and receptors have been discovered in many mammalian species, such as humans, mice, rats, pigs, and cows. However, there is still a lack of information concerning NK cell markers or receptors in canines. We have discovered that canine CD5-low density (CD5lo) cells in PBL are closely associated with NK cell characteristics. CD5lo cells comprised 14.9 +/- 6.68% of the total PBL. A high proportion of the CD5lo cell population expressed CD3 (96.6%), CD8alpha (77.7%), CD8beta (53%), alpha/beta TCR (83%), and CD11/18 (80%), but the expression of gamma/delta TCR (6.5%), CD4 (10.6%), and CD21 (2.4%) was low. CD5lo cells were larger than CD5-high density (CD5hi) cells. Light and electron microscopy revealed numerous large cytoplasmic granules in CD5lo cells, especially after IL-2 stimulation, which was in contrast to CD5hi, in which intracytoplasmic granules were not frequently seen. After IL-2 stimulation, CD5lo cells had significantly stronger NK cytotoxicity than CD5hi cells. CD5lo cells had much higher mRNA levels for NKG2D, CD16, CD94, CD160, perforin, and granzyme than CD5hi. Following IL-2 stimulation, CD5lo cells had significantly higher mRNA levels of NKp30, NKp44, CD16, and CD94 than CD5hi cells. In addition, IL-2-stimulated, CD5lo-depleted PBL showed a loss of NK cytotoxicity. CD5lo cells also showed significantly lower antigen-specific cytotoxic T cell activity as compared with CD5hi cells. Taken together, the CD5lo subset in canine PBL is closely related to canine NK cells, and CD5lo can be used as a phenotypic marker for an IL-2-dependent canine NK cell enrichment.

Forward and backward terahertz-wave difference-frequency generations from periodically poled lithium niobate

We report terahertz-wave generation in the wavelength range of 190 - 210 and 457 - 507 microm from forward and backward difference frequency generations, respectively, in a 3.2-cm long multi-grating periodically poled lithium niobate (PPLN) crystal. The grating period of the PPLN crystal varies form 63 to 70 microm in 1-microm increments. The extraordinary refractive index of lithium niobate in the THz-wave range was precisely deduced from the quasi-phase-matching condition of the difference frequency generations.

The hippo pathway promotes Notch signaling in regulation of cell differentiation, proliferation, and oocyte polarity

Specification of the anterior-posterior axis in Drosophila oocytes requires proper communication between the germ-line cells and the somatically derived follicular epithelial cells. Multiple signaling pathways, including Notch, contribute to oocyte polarity formation by controlling the temporal and spatial pattern of follicle cell differentiation and proliferation. Here we show that the newly identified Hippo tumor-suppressor pathway plays a crucial role in the posterior follicle cells in the regulation of oocyte polarity. Disruption of the Hippo pathway, including major components Hippo, Salvador, and Warts, results in aberrant follicle-cell differentiation and proliferation and dramatic disruption of the oocyte anterior-posterior axis. These phenotypes are related to defective Notch signaling in follicle cells, because misexpression of a constitutively active form of Notch alleviates the oocyte polarity defects. We also find that follicle cells defective in Hippo signaling accumulate the Notch receptor and display defects in endocytosis markers. Our findings suggest that the interaction between Hippo and classic developmental pathways such as Notch is critical to spatial and temporal regulation of differentiation and proliferation and is essential for development of the body axes in Drosophila.

Magnetic and quantum confinement effects on electronic and optical properties of graphene ribbons

Through the tight-binding calculation, we demonstrate that magnetic and quantum confinements have a great influence on the low-energy band structures of one-dimensional (1D) armchair graphene ribbons. The magnetic field first changes 1D parabolic bands into the Hall-edge states which originate in the Landau wavefunctions deformed by one or two ribbon edges. The quantum confinement dominates the characteristics of the Hall-edge states only when the Landau wavefunctions touch two ribbon edges. Then, some of the Hall-edge states evolve as the Landau states when the field strength grows. The partial flat bands (Landau levels), related to the Landau states, appear. The magnetic field dramatically modifies the energy dispersions and it changes the size of the bandgap, shifts the band-edge states, destroys the degeneracy of the energy bands, induces the semiconductor-metal transition and generates the partial flat bands. The above-mentioned magneto-electronic properties are completely reflected in the low-frequency absorption spectra--the shift of peak position, the change of peak symmetry, the alteration of peak height, the generation of new peaks and the change of absorption edges. As a result, there are magnetic-field-dependent absorption frequencies. The findings show that the magnetic field could be used to modulate the electronic properties and the absorption spectra.

Monolithically integrated laser Bragg Q-switch and wavelength converter in a PPLN crystal

We report a periodically poled lithium niobate (PPLN) crystal for both temperature-insensitive laser Q-switching and temperature-tuned wavelength conversion. The PPLN crystal consists of two sections, a 20.3-mum period section functioning as an electro-optic Bragg grating for Qswitching a diode-pumped Nd:YVO4 laser at 1064 nm and a 31-mum-period section functioning as an optical parametric generator for down converting the generated 1064-nm laser. When driving the PPLN Bragg grating with 170-V voltage pulses, we measured 181 muJ pulse energy at 1064 nm from the Nd:YVO4 laser pumped by 20.4 W diode power. The 181-muJ pulsed laser was further converted into mid-infrared radiation in the monolithic PPLN crystal with 35% parametric efficiency. The wavelengths were broadly tunable in the range of 1.75-1.88 mum (signal) and 2.7-2.44 mum (idler) via temperature without affecting the performance of the PPLN Bragg Qswitch.

Average-power mediated ultrafast laser osteotomy using a mode-locked Nd:YVO4 laser oscillator

By using a novel temporal characterization technique, we determined that a threshold average laser power of 160 mW is required to drill through a 0.75-mm-thick cortical bone for a Nd:YVO(4) mode-locked laser oscillator with a peak intensity of 1.3 GWcm(2). The ablation mechanism is identified as average-power induced carbonization followed by peak-power induced avalanche ionization in the carbonized osseous tissue.

Development of a novel bioreactor for the mechanical loading of tissue-engineered heart muscle

OBJECTIVE

In this study, we describe a novel bioreactor system to deliver controlled stretch protocols to bioengineered heart muscle (BEHM) constructs. Our primary objective was to evaluate the effect of mechanical stretch on the contractile properties of three-dimensional cardiac constructs in vitro.

METHODS

BEHMs were formed by culturing primary neonatal cardiac myocytes in a fibrin gel using a method previously developed in our laboratory. A custom bioreactor system was designed using SolidWorks (Concord, MA) and structural components were manufactured using fusion deposition modeling. We utilized the bioreactor to evaluate the effect of 2-, 6-, and 24-hour stretch protocols on the stretch-induced changes in contractile function of BEHMs.

RESULTS

We were able to demonstrate compatibility of the bioreactor system with BEHMs and were able to stretch all the constructs with zero incidence of failure. We found that loading the constructs for 2, 6, and 24 hours during a 24-hour period using a stretch protocol of 1 Hz, 10% stretch did not result in any significant change in the active force, specific force, pacing characteristics, and morphological features.

CONCLUSIONS

In this study, we demonstrate compatibility of a novel bioreactor system with BEHMs and the stability of the BEHMs in response to stretch protocols.

Electro-optic narrowband multi-wavelength filter in aperiodically poled lithium niobate

We report on an iterative design scheme for and the first experimental demonstration of active narrowband multi-wavelength filters based on aperiodically poled lithium niobate crystals. A simultaneous transmission of 8 wavelengths, each with a ~0.45-nm linewidth and nearly 100% peak transmittance, was achieved in such a device. The transmission spectrum of this device can be tuned by temperature at a rate of ~0.65 nm/ degrees C.

Electro-optic Ti:PPLN waveguide as efficient optical wavelength filter and polarization mode converter

We report the first experimental demonstration of electrically controlled Solc-type optical wavelength filters and TE-TM mode converters based on Ti-diffused periodically poled lithium niobate (Ti:PPLN) waveguides. A maximum mode conversion efficiency or a peak spectral transmittance of ~99% in the telecom C-L bands was obtained from a 9-mm long, 21.5-21.8-mum multiple-grating Ti:PPLN waveguide device with a switching voltage of as low as 22 V or 0.99 Vxd(mum)/L(cm), where d is the electrode separation and L is the electrode length. The spectral range of this device can be tuned by temperature at a rate of ~0.758 nm/ degrees C.

Electro-optic periodically poled lithium niobate Bragg modulator as a laser Q-switch

We report an electro-optic Bragg modulator using a periodically poled lithium niobate (PPLN) crystal. We measured a half-wave voltage of 160 V when transmitting a 1064 nm laser through a 14.2 mm long, 780 microm thick, 20.13 microm period PPLN crystal at the Bragg angle. We also demonstrated a Q-switched Nd:YVO(4) laser using such a PPLN Bragg modulator as its Q-switch, producing 7.8 ns, 201 microJ pulses at a 10 kHz repetition rate when pumped by a 19.35 W diode laser at 808 nm.