Generation of polarization-entangled photon pairs via concurrent spontaneous parametric downconversions in a single χ(2) nonlinear photonic crystal

We propose a scheme for generating polarization-entangled photon pairs using a χ((2)) nonlinear photonic crystal, which is designed for enabling two concurrent quasi-phase-matched spontaneous parametric downconversion processes. Beamlike photon pairs produced from each process are collinear but noncollinear with the pump. Moreover, the source we design works in a postselection-free way and applies to both degenerate and nondegenerate cases. Combining possible waveguide technologies, our scheme may provide an integrated polarization entanglement source.

MicroRNA-155 inhibits proliferation and migration of human extravillous trophoblast derived HTR-8/SVneo cells via down-regulating cyclin D1

MiR-155 is known to participate in various cellular processes by targeting gene expression. We previously revealed a link between miR-155 and perturbation of trophoblast invasion and differentiation. This study aimed to investigate the target molecule(s) of miR-155 on the influence on the proliferation and migration of trophoblast cells. Bioinformatics analysis showed that, at the 3' untranslated region (UTR) of cyclin D1, six bases are complementary to the seed region of miR-155. Luciferase assays and cyclin D1 3'UTR transfection assays validated that cyclin D1 3'UTR was the target of miR-155 in HTR-8/SVneo cells. Overexpression of miR-155 in HTR-8/SVneo cells reduced the level of cyclin D1 protein, decreased cell proliferation and invasion, and increased cell number at the G1 stage. Furthermore, the increased expression of miR-155 also regulated the protein levels of kinase inhibitory protein p27 and phosphorylated cytoskeletal protein filamin A. In conclusion, we found that cyclin D1 may be a target of miR-155 in HTR-8/SVneo cells, and demonstrated a negative regulatory role of miR-155 involved in cyclin D1/p27 pathway in proliferation and migration of the cells.

Identification of genes preferentially expressed in goat hair follicle anagen-catagen transition using suppression subtractive hybridization

Suppressive subtraction hybridization (SSH) was used to identify differentially expressed genes in goat (Capra hircus) hair follicle anagen-catagen transition. The cDNA fragments, derived from SSH positive subtractive library (tester: anagen-catagen transition, driver: later anagen), were cloned into pEGM-T vector. Two hundred cDNA fragments screened from this library were subjected to identify forty-five unregulated isolates. Sequence analysis revealed that these fragments represented twenty-three genes. Blasting analysis with database in GenBank showed that twenty genes were previously clearly annotated, two were homologous to un-annotated expressed sequence tag (ESTs), and one might be novel. To identify characters of gene expression, seven genes in later anagen and anagen-catagen transition skin tissues were chosen for quantitative real-time PCR. Results indicated that expression of these seven genes varied much, reaching threefold among them, furthering indicating that expression of those genes was up-regulation in the anagen-catagen transition. We characterized expression levels of this potential novel gene and the goat ectodysplasin A during differential stages of hair cycle. These profiles suggested that these two genes might play a role in the goat secondary hair follicle cycle.

Short-term administration of ACTH improves plasma lipid profile and renal function in kidney transplant patients

The present study investigated effects of short-term administration of adrenocorticotrophic hormone (ACTH) on blood lipid profile and renal function in kidney transplant patients. Six patients who had kidney transplantations 2 to 10 years earlier received ACTH intramuscularly (1 mg/d) for 4 days. We analyzed serum levels of lipids, lipoproteins, apolipoproteins, blood creatinine, and other parameters. Short-term ACTH treatment significantly decreased serum apolipoprotein B and apolipoprotein AI, whereas it significantly increased plasma high-density lipoproteins (HDL). Interestingly, creatinine level moderately decreased and creatinine clearances moderately increased among five of six patients. Hepatic function and serum concentration of cyclosporine did not change. There were no serious side effects during ACTH treatment. It was concluded that ACTH treatment had beneficial effects on serum lipoprotein profile, potentially improving renal function in kidney transplant patients. Further observations are needed to confirm these effects.

Management of pediatric radiation dose using GE's Revolution digital radiography systems

Digital flat-panel x-ray detectors offer excellent image quality and dose efficiency in addition to clinical productivity, connectivity, and adaptability to advanced clinical applications. GE's Revolution systems provide two modes of exposure control for setting the dose operating point, fixed time and automatic exposure control, the latter of which maintains high image signal-to-noise ratio for the given technique settings. In addition to enhancing detail contrast and compressing the dynamic range, postprocessing automatically determines the best window level and width for display, taking into account the dose at which the image was acquired. Several studies have examined the reduction in patient dose achievable with Revolution systems as compared to competing technologies, and results indicate significant dose savings with equivalent or superior image quality. For pediatric exams, pediatric default techniques provide for a lower patient dose as compared to adult techniques. Therefore, GE's Revolution systems can achieve a high image quality-to-dose ratio for pediatric imaging using the combined advantages of dose-efficient detection, advanced postprocessing, and independently adjustable pediatric techniques.

[Influence of a triplex superimposed treatment on HBV replication and mutation during treating chronic hepatitis B]

OBJECTIVE

To observe and evaluate the influence of a new antiviral treatment scheme on HBV replication and mutation during treating chronic hepatitis B.

METHODS

In the test group, lamivudine, IFN alpha-2b, Astragalus membranaceus were chosen as a triplex superimposed treatment scheme for treating the patients who were on the state of HBV high replication and involved in the clinical condition of chronic hepatitis B. The control group was treated with lamivudine alone. The observed parameters percentage of patients in whom HBV DNA became undetectable (serum HBV DNA<1.6 ng/L), HBeAg/anti-HBe seroconversion rate; HBV DNA serum level; HBV YMDD mutation rate and pre-C region mutation rate.

RESULTS

Compared with that of the control group, HBV DNA undetectable rate of the test group increased markedly at weeks 12, 36, 48(P <0.05), HBeAg negative rate of the group increased markedly at week 36, 48(P <0.05), while anti-HBe positive rate increased only at week 48 (31.58 vs.19.23%, P <0.05). After 4 weeks of treatment, HBV DNA serum level of both the test group and the control group reduced very remarkably (P <0.01), and at week 48, reduced more significantly (P <0.001). Compared with the control group, HBV DNA serum level of the test group reduced notably at week 12 (P <0.05) and very notable at week 36 and 48(P <0.01). At week 12, the pre-C region mutation occurred in the test group, and at week 24, 36,48, the pre-C region and YMDD mutations occurred in both the test group and the control group.

CONCLUSIONS

As to anti-viral treatment of chronic hepatitis B, the triplex superimposed treatment had better efficacy than lamivudine alone.

How to optimize OCT image

Quantization, which maps real values of raw data to a series of fixed gray levels, is an inevitable step in Optical Coherence Tomography (OCT) image formation. Three new quantization methods, Minimum Distortion, Information Expansion and Maximum Entropy are applied in the specific problem. Quantization results of a capillary with milk and the femoralis of rabbit are shown in this paper. Comparisons with the present log-based methods show that a suitable quantization method significantly increases contrast, SNR and visual fineness of the final image and reduces quantization error effectively. Applicability of different quantization methods is also discussed.

Study of the electrochemical behavior of mitoxantrone and its determination at a Co-C modified ultramicroelectrode

In 0.005 mol dm-3 Tris-0.05 mol dm-3 NaCl buffer solution (pH 7.10), the electrochemical behavior of mitoxantrone was studied by linear-sweep voltammetry and cyclic voltammetry at a Co-carbon fiber ion implantation modified ultramicroelectrode. A sensitive reduction peak was obtained. The peak potential was -0.798 V (vs. SCE), the peak current was proportional to the concentration of mitoxantrone over the range of 2.0 x 10(-7)-6.0 x 10(6) mol dm-3 and the detection limit was 4.2 x 10(-8) mol dm-3. This method was applied to the direct determination of mitoxantrone in urine. Recoveries were in the range 95.4-105.8%. The reduction process was quasi-reversible with absorptive characteristics at a Co-C ultramicroelectrode. According to Laviron's theory, the electrode reaction rate constant ks and the electron transfer alpha of mitoxantrone were 4.4 s-1 and 0.48, respectively. The composition and depth distribution of elements on the surface of the Co-C ultramicroelectrode were determined by Auger electron spectroscopy. The experiments showed that Co was implanted into the surface of the carbon fiber, and the Co-C ultramicroelectrode had good stability and reproducibility.

Dose efficiency and low-contrast detectability of an amorphous silicon x-ray detector for digital radiography

The effect of dose reduction on low-contrast detectability is investigated theoretically and experimentally for a production grade amorphous silicon (a-Si) x-ray detector and compared with a standard thoracic screen-film combination. A non-prewhitening matched filter observer model modified to include a spatial response function and internal noise for the human visual system (HVS) is used to calculate a signal-to-noise ratio (SNR) related to object detectability. Other inputs to the SNR calculation are the detective quantum efficiency (DQE) and the modulation transfer function (MTF) of the imaging system. Besides threshold detectability, the model predicts the equivalent perception dose ratio (EPDR), which is the fraction of the screen film exposure for which the digital detector provides equal detectability. Images of a contrast-detail phantom are obtained with the digital detector at dose levels corresponding to 27%, 41%, 63% and 100% of the dose used for screen-film. The images are used in a four-alternative forced choice (4-AFC) observer perception study in order to measure threshold detectability. A statistically significant improvement in contrast detectability is measured with the digital detector at 100% and 63% of the screen-film dose. There is no statistical difference between screen-film and digital at 41% of the dose. On average, the experimental EPDR is 44%, which agrees well with the model prediction of 40%.

[Changes in serum levels of total amino acids in young children with congenital heart diseases]

OBJECTIVE

To study the implication of early surgical operation on the improvement of protein malnutrition in young children with congenital heart diseases.

METHODS

Sixteen kinds of serum free amino acids were determined with an automatic analyzer for 72 cases with congenital heart diseases before and after surgical operation and 51 healthy children.

RESULTS

Serum total amount of essential amino acids reduced in children with congenital heart diseases, mainly of branch-chained amino acids, especially significant in young ones. Serum amino acids restored to normal level one month after surgical operation.

CONCLUSION

There existed protein malnutrition in children with congenital heart diseases, especially in young ones. Surgical operation for them in a suitable time will improve their protein nutritional status.

Effects of motion blurring in x-ray fluoroscopy

In conventional fluoroscopy, continuous x-ray exposure blurs moving objects, while in pulsed fluoroscopy, short duration x-ray pulses acquire images without motion blur. Many perception experiments on noisy image sequences are consistent with low-pass temporal filtering by the human visual system, and this is anticipated to cause visual system "blurring" of moving objects. With moving cylinders in spatially white noise, we simulated 30 acq/s (acquisitions per second), continuous fluoroscopy having both x-ray and visual system motion blur. We also simulated pulsed fluoroscopy at 30 acq/s (pulsed-30) having visual system but not x-ray system motion blur. For both continuous and pulsed-30 acquisitions, with increasing velocity, detectability of small cylinders decreased by as much as approximately 50%, while detectability of large cylinders increased and then decreased. Detectability of pulsed-30 was only slightly higher than continuous, indicating that visual system motion blurring dominated x-ray system blurring. For the case of stationary objects, blurring greatly reduced detectability, indicating that last-image-hold of moving objects deteriorates with continuous acquisitions. With no free parameters, a human observer model with an independently measured spatio-temporal contrast sensitivity function accurately described all effects.

Detection of moving objects in pulsed-x-ray fluoroscopy

We investigated the detectability of moving, low-contrast objects in white-noise image sequences. The computer-generated, cylindrical phantoms mimicked arteries, catheters, and guide wires in medical, x-ray fluoroscopy image sequences at 16 acquisitions/s (pulsed-16) or 32 acquisitions/s (pulsed-32). We measured detectability by using a reference-test, adaptive forced-choice method whereby reference and test presentations were alternated during an experimental session to minimize effects of subject attention and accuracy criteria. In the case of the largest cylinder (diameter 0.48 deg), the highest speed (5.86 deg/s) increased absolute detectability by approximately 42% compared with that in the stationary case. With the smallest cylinder (diameter 0.023 deg), this motion decreased detectability by approximately 51%. The dose savings of pulsed-16 was approximately 18% of that for pulsed-32, with relatively little effect of velocity or object size. In general, subjects took slightly longer to respond in the case of low-acquisition fluoroscopy. Detectability data were modeled with a nonprewhitening matched filter that included a physiological, spatiotemporal contrast sensitivity function and a suboptimal, spatiotemporal signal template with time-limited memory.

International clinical trials of HIV vaccines: II. phase I trial of an HIV-1 synthetic peptide vaccine evaluating an accelerated immunization schedule in Yunnan, China

A Phase 1, double-blind, placebo controlled trial was conducted in Longchuan County, China, to evaluate the safety and immunogenicity of a prototype HIV-1 synthetic peptide vaccine in a target population at risk for HIV infection, and to establish the infrastructure for future large-scale HIV vaccine efficacy trials. Subjects were randomly assigned to receive 100 microg or 500 microg of vaccine or alum placebo, and were given three injections at an accelerated 0, 1, and 2 month schedule. The vaccine was well tolerated with no significant local or systemic reactions observed in any subjects. Fifty-five percent (100 microg dose) and 64% (500 microg dose) of subjects who received the vaccine produced binding antibody to the immunogen as determined by ELISA. However, HIV-1 (MN) neutralizing antibody was detected in only 23% (3/13) of subjects with detectable HIV-1 specific binding antibody. It was concluded that this prototype HIV-1 synthetic peptide vaccine was well tolerated, safe and immunogenic, and that a 0, 1, 2 month schedule was not as effective in stimulating HIV-1 specific neutralizing antibodies compared with previous trials utilizing a 0, 1, 6 month schedule. Finally, this trial demonstrated that well-designed HIV vaccine trials can be performed at this clinical trials site in Yunnan, China, and that this site should be considered for conducting larger safety, immunogenicity and efficacy trials of candidate HIV vaccines.

Pulsed fluoroscopy detectability from interspersed adaptive forced-choice measurements

Using a new reference/test, adaptive forced-choice method, we investigated detectability of low contrast disks in simulated x-ray fluoroscopy image sequences. The method minimized effects of undesirable variables, such as changes in subject attention level by alternating conventional fluoroscopy (reference) and low acquisition rate fluoroscopy (test) presentations. To compare absolute target detectability and x-ray dose requirements of reference and test presentations, the contrast of the test presentation was set equal to that of the reference presentation, and the dose of the test presentation was adapted to give equivalent detectability of disk targets. Comparing pulsed fluoroscopy at 15 acq/s (pulsed-15) and 7.5 acq/s (pulsed-7.5) with conventional fluoroscopy at 30 acq/s (pulsed-30), dose savings were found in 22 of 24 experiments. When averaged over 3 disk sizes and 4 subjects, savings were 22% and 26% for pulsed-15 and pulsed-7.5, respectively. In most experiments, the subject was given an unlimited time to view presentations. With unlimited display times, subjects took slightly longer to respond for pulsed-15 or pulsed-7.5 than for pulsed-30. In other experiments, display times were limited. As the restricted display time increased, absolute target detectability increased while the x-ray dose for equivalent detectability was unchanged. The number of frames, N, in a repeating loop was also varied. Absolute detectability increased as N increased from 1 to 30 but changed little as more frames were added up to 150. The new experimental paradigm gives efficient, robust comparisons of image data and is applicable to a wide variety of medical image perception problems.

Experimental Campylobacter jejuni infection in the chicken: an animal model of axonal Guillain-Barré syndrome

OBJECTIVE

To develop and characterise an animal model of paralytic neuropathy after Campylobacter jejuni infection. Campylobacter infection precedes development of many cases of Guillain-Barré syndrome and is particularly associated with cases having prominent axonal degeneration. Understanding the pathogenesis of Guillain-Barré syndrome after C jejuni infection has been slowed by the lack of animal models.

METHODS

A spontaneous paralytic neuropathy is described that developed in chickens from the farms of four patients with Guillain-Barré syndrome. The production of paralytic neuropathy in chickens experimentally fed Campylobacter jejuni isolated from one of these patients is reported. The sciatic nerves of the spontaneously paralysed chickens were examined pathologically in teased fibres, in plastic embedded sections, and by electron microscopy. Two large groups of chickens were then fed cultures of a C jejuni (Penner type O:19) isolated from one of these patients.

RESULTS

The chickens with spontaneous paralysis had pathologically noninflammatory neuropathy. Pathology in the sciatic nerves ranged from no detectable changes to severe Wallerian-like degeneration. In the experimentally inoculated groups, an average of 33% of the chickens became paralysed. The median time after inoculation to paralysis was 12 days. The lesions found in the first few days of paralysis included nodal lengthening and paranodal demyelination. In those animals that survived for several days after onset of weakness, the pathology was dominated by extensive Wallerian-like degeneration. Animals that survived for weeks with no clinically apparent neuropathy had paranodal remyelination in some teased nerve fibres, reflecting earlier paranodal demyelination.

CONCLUSION

Experimental inoculation with C jejuni may provide a new model for understanding some forms of Guillain-Barré syndrome.