[Computer simulation of molecular docking between methylene blue and some proteins of Porphyromonas gingivalis].

OBJECTIVE: To study the binding target of photosensitizer and bacteria in antimicrobial photodynamic therapy with computer-simulated target prediction and molecular docking research methods and to calculate the binding energy. METHODS: The protein names of Porphyromonas gingivalis (Pg) were obtained and summarized in Uniprot database and RCSB PDB database; the structure diagrams of methy-lene blue were screened in SciFinder database, PubChem database, ChemSpider database, and Chemical Book, and ChemBioDraw software was used to draw and confirm the three-dimensional structure for target prediction and Cytoscape software was used to build a visual network diagram; a protein interaction network was searched and built between the methylene blue target and the common target of Pg in the String database; then we selected FimA, Mfa4, RgpB, and Kgp K1 proteins, used AutoDock software to calculate the docking energy of methylene blue and the above-mentioned proteins and performed molecular docking. RESULTS: The target prediction results showed that there were 19 common targets between the 268 potential targets of methylene blue and 1 865 Pg proteins. The 19 targets were: groS, radA, rplA, dps, fabH, pyrG, thyA, panC, RHO, frdA, ileS, bioA, def, ddl, TPR, murA, lepB, cobT, and gyrB. The results of the molecular docking showed that methylene blue could bind to 9 sites of FimA protein, with a binding energy of -6.26 kcal/mol; with 4 sites of Mfa4 protein and hydrogen bond formation site GLU47, and the binding energy of -5.91 kcal/mol, the binding energy of LYS80, the hydrogen bond forming site of RgpB protein, was -5.14 kcal/mol, and the binding energy of 6 sites of Kgp K1 protein and the hydrogen bond forming site GLY1114 of -5.07 kcal/mol. CONCLUSION: Computer simulation of target prediction and molecular docking technology can initially reveal the binding, degree of binding and binding sites of methylene blue and Pg proteins. This method provides a reference for future research on the screening of binding sites of photosensitizers to cells and bacteria.

Effect of BDNF-TrKB pathway on apoptosis of retinal ganglion cells in glaucomatous animal model.

OBJECTIVE: The aim of this paper is to investigate the effect of BDNF-TrKB pathway on AOH by accessing its regulatory role in retinal ganglion cell apoptosis. MATERIALS AND METHODS: Acute ocular hypertension (AOH) model in rats was established by anterior chamber perfusion to increase intraocular tension. Rats were randomly divided into AOH group, control group and k252a group, with ten rats in each group. Rats were sacrificed 72 h after animal procedures and eyeballs were harvested. HE staining was used to observe retinal structural changes at different time points. Immunohistochemical staining was used to observe the BDNF-positive cells in retinal tissues. TUNEL staining was conducted to measure apoptosis of retinal ganglion cells. Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) and Western blot were performed to detect mRNA and protein levels of BDNF, TrKB, PI3K and ERK1 in retinal tissues, respectively. RESULTS: HE and TUNEL staining showed significant pathological changes and abundant apoptotic cells in rat retina of AOH group and k252a group compared with those of the control group (p<0.05). The number of survived retinal ganglion cells in the AOH group was lower than that of the control group (p<0.05). K252a group had the lowest number of survived retinal ganglion cells. Immunohistochemical results showed that BDNF was rarely expressed in rat retinal tissues of the control group, which was remarkably pronounced in the AOH group and k252a group. The number of BDNF-positive cells in the k252a group was higher than that in the AOH group (p<0.05). RT-PCR and Western blot indicated that mRNA and protein levels of relative genes in BDNF-TrKB and PI3K/ERK1 pathways were upregulated in AOH group (p<0.05), but were significantly downregulated in k252a group (p<0.05). CONCLUSIONS: BNDF-TrKB pathway exerts a protective effect on retina against acute ocular hypertension by reducing retinal cell apoptosis.

Knockdown of thrombospondin 2 inhibits metastasis through modulation of PI3K signaling pathway in uveal melanoma cell line M23.

OBJECTIVE: Thrombospondin 2 (THBS2) expression and its prognostic value have been documented in several types of cancer. Nevertheless, the potential role and clinical significance of THBS2 in uveal melanoma (UM) have never been reported. Thus, in our study, we aimed to explore the clinical significance and prognostic impact of THBS2 in UM. MATERIALS AND METHODS: Survival and prognosis analyses were implemented using the Kaplan-Meier method and COX's proportional hazards model based on the clinical data retrieved from The Cancer Genome Atlas (TCGA) database. Colony formation, cell proliferation, invasion and migration assays in M23 cell line were performed to evaluate the effects of THBS2 on UM in vitro. To further reveal whether the dysregulated THBS2 expression regulates the UM metastasis, protein biomarkers including serine-threonine kinase (AKT), p-AKT, phosphoinositide 3-kinase (PI3K), p-PI3K, and p70S6K were measured using Western blotting analysis. RESULTS: THBS2 was up-regulated in metastatic UMs. Relationship of THBS2 expression level with the clinicopathological factors demonstrated that the expression level of THBS2 was significantly correlated to histological type, recurrence, and dead. Univariate as well as multivariate COX analyses demonstrated that THBS2 could serve as an independent prognostic factor for overall survival of UM. The knockdown of THBS2 significantly inhibited the proliferation rate of M23 cells, suppressed the colony numbers of M23 cells, lowered the invasive and migratory cell proportion. Importantly, Western blotting results implicated that THBS2 knockdown significantly decreased the expression level of p-AKT, p-PI3K, and p70S6K in M23 cell line. CONCLUSIONS: This is the first study to report that THBS2 may play important roles in UM progression and might be a novel prognosis biomarker for UM.

Melatonin regulates traumatic optic neuropathy via targeting autophagy.

OBJECTIVE: Traumatic optic neuropathy (TON) usually refers to the indirect damage to the optical nerve, which can cause partial or complete blindness. Melatonin (MT) is a kind of indole hormone, and the retina is one of its natural sites of secretion in the human body. This study aims to explore MT in the retina and optic nerve injuries due to TON. MATERIALS AND METHODS: Sprague-Dawley (SD) rats were used for TON model in the study. After operation, rats were treated with MT or phosphate buffered saline (PBS) for 4, 7, 14, 21, and 28 days before sacrifice. The changes in retinal ganglion cells (RGCs) were observed via hematoxylin-eosin (HE) staining. Terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) staining was applied to observe apoptosis. Immunofluorescence staining was applied to detect caspase-3 and Western blot was used to detect LC3, cleaved caspase-3 and glyceraldehyde phosphate dehydrogenase (GAPDH). RESULTS: The number of RGCs in MT group increased compared to the model group. After MT treatment, the increased number of TUNEL positive cells and the increased number of caspase-3 positive cells in the retina of MT group was alleviated. Moreover, Western blot analysis revealed that the LC3-II/LC3-I ratio in the retinal tissue of MT group was further increased, while the increased cleaved caspase-3 protein level in the retina of MT group was alleviated compared to the model group. CONCLUSIONS: The results of this study revealed that MT therapy affects the apoptosis level of RGCs after TON through alleviating the increased caspase-3 protein level. Its mechanism may be that it further up-regulates the autophagy level of RGCs after TON, ultimately inhibiting the apoptosis of RGCs after TON and playing a neuroprotective role.

Hyperhomocysteinemia Is Associated with Vitamin B-12 Deficiency: A Cross-sectional Study in a Rural, Elderly Population of Shanxi China.

OBJECTIVES: To report the association of lifestyle factors and plasma vitamin B-12 with hyperhomocysteinemia in a large sample of men and women living in a region of China where there is an increased risk of NTDs. DESIGN: Community-based, cross-sectional study of Lvliang City, Shanxi Province, China. SETTING: Hyperhomocysteinemia is an independent risk factor for cardiovascular disease (CVD) and a sensitive marker of vitamin B-12 and folate deficiency. PARTICIPANTS: A total of 2355 (1044 men and 1311 women) participants born before 1 January 1958 (≥55 years of age) and living in Lvliang City for at least 2 months a year were included. MEASUREMENTS: The participants were assessed regarding demographic characteristics, height, weight, as well as having a physical examination and blood sampling for serum cholesterol, total homocysteine (tHcy), folate, and vitamin B12 levels. RESULTS: The median (25th-75th percentile) tHcy concentration was 21.5 (15.8-33.6) µmol/L in men and 18.0 (13.4-24.8) µmol/L in women. The overall prevalence of hyperhomocysteinemia (tHcy ≥15 µmol/L) was 72.6% (84.3% in men and 63.2% in women), inversely correlated with folate (r=-0.230, P=0.006) and vitamin B-12 (r=-0.540, P<0.001), and positively correlated with uric acid (r=0.054, P<0.001). Vitamin B-12 and folate deficiency, older age, and male gender were associated with elevated tHcy; with vitamin B-12 deficiency being the strongest. CONCLUSIONS: Plasma tHcy concentration and hyperhomocysteinemia were significantly higher in this population than in previously studied populations. Vitamin B-12 and folate supplementation, concomitant lifestyle changes such as smoking cessation, and lipid-lowering treatments may help to decrease plasma tHcy concentrations and reduce the CVD risk in this population.

Nutritional status of the elderly in rural North China: a cross-sectional study.

OBJECTIVES: This study aimed to describe the nutritional status of elderly people living in a rural area of North China. DESIGN: Community-based, cross-sectional prevalence survey. SETTING: 3 rural towns of Lvliang City, Shanxi Province, China. PARTICIPANTS: A sample of 1845 community residents (29.1% of those eligible) 55 years or older (birth before 1958-01-01). MEASUREMENTS: The participants were assessed regarding demographic characteristics, height, weight, as well as having a physical examination and blood sampling for serum cholesterol, total homocysteine (tHcy), folate, and vitamin B12 levels. RESULTS: 991 (53.7%) were female and 139 (7.5%) did not complete the anthropometric measurement. Prevalence of underweight and obesity was 3.5% and 24.9% in men and 6.7% and 31.0% in women (P = 0.003, P = 0.005, respectively). Prevalence of hypercholesterolemia and hypocholesterolemia was 13.5% and 52.6% in men and 25.0% and 34.3% in women (P < 0.001, P < 0.001, respectively). Prevalence of high LDL-c concentrations was 8.8% in men and 16.8% in women (P < 0.001). The mean serum tHcy in men (28.8 ± 20.1 µmmol/l) was significantly higher than in women (21.0 ± 15.1 µmmol/L, P < 0.001). Prevalence of hyperhomocysteinemia (defined as > 15µmmol/L) was 79.7% in men and 65.5% in women (P < 0.001). Prevalence of low folate (defined as < 11 nmol/L) and vitamin B12 levels (defiend as < 185 pmol/L) was 70.8 % and 76.8% in men and 56.5% and 72.6% in women (P < 0.001, P = 0.036, respectively). Correlation coefficients between tHcy, folate, and vitamin B12 indicated an inverse linear correlation (r = -0.21, P < 0.001, r = -0.35, P < 0.001, respectively). CONCLUSIONS: As China's economic climate has developed, the nutritional status of elderly people in the rural parts of the country has improved in some aspects. However, the trend toward obesity will lead to a shift in the burden of obesity-related chronic diseases. In addition, rurally-located elderly people are at high risk of death that may be associated with abnormal serum cholesterol. The data also suggest that severe deficiencies in folate and vitamin B12 levels exist, as well as there being a high prevalence of hyperhomocysteinemia. Folate and vitamin B12 supplementation are necessary to prevent related diseases.

Experimental implementation of optical clockwork without carrier-envelope phase control.

We demonstrate optical clockwork without the need for carrier-envelope phase control by use of sum-frequency generation between a continuous-wave optical parametric oscillator at 3.39 microm and a femtosecond mode-locked Ti:sapphire laser with two strong spectral peaks at 834 and 670 nm, a spectral difference matched by the 3.39-microm radiation.

Phase-coherent optical pulse synthesis from separate femtosecond lasers.

We generated a coherently synthesized optical pulse from two independent mode-locked femtosecond lasers, providing a route to extend the coherent bandwidth available for ultrafast science. The two separate lasers (one centered at 760 nanometers wavelength, the other at 810 nanometers) are tightly synchronized and phase-locked. Coherence between the two lasers is demonstrated via spectral interferometry and second-order field cross-correlation. Measurements reveal a coherently synthesized pulse that has a temporally narrower second-order autocorrelation width and that exhibits a larger amplitude than the individual laser outputs. This work represents a new and flexible approach to the synthesis of coherent light.

Molecular iodine clock.

We demonstrate a simple optical clock based on an optical transition of iodine molecules, providing a frequency stability superior to most rf sources. Combined with a femtosecond-laser-based optical comb to provide the phase coherent clock mechanism linking the optical and microwave spectra, we derive an rf clock signal of comparable stability over an extended period. Measurements suggest the stability ( 5x10(-14) at 1 s) of the cw laser locked on the iodine transition is transferred to every comb component throughout the optical octave bandwidth (from 532 to 1064 nm) with a precision of 3.5x10(-15). Characterization of the performance of the optical clock shows (in-)stability below 3x10(-13) at 1 s (currently limited by the microwave sources), and 4.6x10(-13) over one year.

[A study on quality standard of Rabdosia lophanthoides (Buch.-Ham. ex D. Don Hara)].

OBJECTIVE: To establish quality standards for safe and correct use of Rabdosia lophanthoides. METHOD: Field investigation and pharmacognostic study. RESULT: R. lophanthoides was confirmed as a derivative of R. lophanthoides. CONCLUSION: A convenient and effective method for identifying the herb has been established.

Optical frequency measurement across a 104-THz gap with a femtosecond laser frequency comb.

The frequency-domain mode comb of a Ti:sapphire femtosecond laser centered at 350 THz is broadened to 150 THz (full width at -30 dBc) by self-phase modulation in a single-mode optical fiber. By phase locking continuous-wave lasers to elements of the comb near 1064 and 778 nm, we measure the 104-THz frequency gap between these two lasers with a relative uncertainty of 2.7 x 10(-11) in 1 s.

Frequency comb generation using femtosecond pulses and cross-phase modulation in optical fiber at arbitrary center frequencies.

A technique is presented for generating optical frequency combs centered at arbitrary wavelengths by use of cross-phase modulation (XPM) between a femtosecond pulse train and a cw laser beam by copropagating these signals through an optical fiber. We report results from use of this method to place a 90-MHz frequency comb on an iodine-stabilized Nd:YAG laser at 1064 nm and on a frequency-doubled Nd:YVO(4) laser at 532 nm. XPM is verified to be the comb-generating process, and the width of the frequency comb is measured and compared with theory. The spacing of the frequency comb is compared with the femtosecond source, and a frequency measurement with this comb is demonstrated.

Broadband optical frequency comb generation with a phase-modulated parametric oscillator.

We introduce a novel broadband optical frequency comb generator consisting of a parametric oscillator with an intracavity electro-optic phase modulator. The parametric oscillator is pumped by 532-nm light and produces near-degenerate signal and idler fields. The modulator generates a comb structure about both the signal and the idler. Coupling between the two families of modes results in a dispersion-limited comb that spans 20 nm (5.3 THz). A signal-to-noise ratio of >30 dB in a 300-kHz bandwidth is observed in the beat frequency between individual comb elements and a reference laser.

Highly selective terahertz optical frequency comb generator.

Using a 10.5-GHz resonant electro-optic modulator placed inside a resonant optical cavity, we generated an optical frequency comb with a span wider than 3 THz. The optical resonator consists of three mirrors, with the output coupler being a thin Fabry-Perot cavity with a free spectral range of 2 THz and a finesse of 400. Tuning this filter cavity onto resonance with a particular high-order sideband permits efficient output coupling of the desired sideband power from the comb generator, while keeping all other sidebands inside for continued comb generation. This spectrally pure output light was then heterodyne detected by another laser with a frequency offset of the order of 1 THz.

Clinical and experimental study on therapeutic effect of Weixibaonizhuanwan on gastric precancerous lesions.

AIM: To study the therapeutic effect of Weixibaonizhuanwan on gastric precancerous lesions. METHODS: Thirty-six patients with gastric precancerous lesions were treated with Weixibaonizhuanwan for 3 mo. Thirteen (36.1%) patients presented with mild atrophic gastritis, 14 (38.9%) with moderate atrophic gastritis, and nine (25.0%) with severe atrophic gastritis. Twenty-two (61.1%) and 27 (75.0%) of the cases were accompanied by intestinal metaplasia (IM) and dysplasia (DYS), respectively. Twenty of the 36 patients were men and 16 were women, ranging from 30 to 67 years in age, with 61.1% of the patients being 40-59 years old. The duration of the disease in these patients ranged from 3 mo to 21 years, with 20 (55.6%) patients experiencing durations of the disease between 5 and 10 years. The clinical manifestations of the disease in these patients included fullness of the abdomen (31 cases), abdominalgia (27 cases), anorexia (30 cases), eructation (26 cases), pantothenic acid (6 cases), and loose stool (9 cases). Patients were treated with Weixibaonizhuanwan and symptom improvement, level of atrophy of the gastric mucosa, and IM and DYS progression were analyzed. RESULTS: After a 3-mo treatment with Weixibaonizhuanwan, seven patients experienced recovery. The treatment was effective in 11 cases, improved symptoms in 13 cases, and was ineffective in five cases. The overall efficacy rate was 86.1%. In patients with mild atrophic gastritis (n = 13), 11 improved into superficial gastritis and two experienced no improvement. In 14 cases of moderate gastritis, four cases improved into superficial gastritis and seven turned into mild atrophic gastritis, with three patients experiencing no improvement. Among severe atrophic gastritis patients (n = 9), five improved into moderate atrophic gastritis after treatment and four experienced no improvement. The overall efficacy rate in chronic atrophic gastritis patients was 77.8%. Among 9 patients with IM, IM disappeared in six cases, whereas three cases showed no improvement after treatment. In cases with moderate IM (n = 10), IM disappeared in two, turned into mild IM in five, and showed no change in three. Out of four cases with IM, one case turned into moderate IM and three showed no change. The overall efficacy rate in IM patients was 63.6%. Out of 16 cases of mild DYS, DYS disappeared in 11, whereas five cases showed no change. Out of nine cases of moderate DYS, DYS disappeared in two and turned into mild DYS in five cases, with two patients experiencing no change after treatment. No improvement was observed in the two cases of severe DYS after treatment. The overall efficacy rate in DYS patients was 66.7%. After treatment, expression of carcinoembryonic antigen (CEA) and proliferating cell nuclear antigen (PCNA) in gastric mucosa significantly decreased (P < 0.01). Before treatment, cancer staging of these patients by positive CEA expression was I, II, III, and IV in 13, 12, 9, and 2 cases, respectively. After treatment, the number of cases per stage changed to 25, 7, 3, and 1, respectively. Similarly, before treatment, staging by positivity of PCNA expression was I, II, III, and IV in 16, 11, 10, and 4 cases, respectively, and changed to 21, 9, 5, and 1, respectively, after treatment. CONCLUSION: The use of Weixibaonizhuanwan in the treatment of gastric precancerous lesions showed promising therapeutic effects in patients after 3-mo treatments.

Sub-Doppler optical frequency reference at 1.064 microm by means of ultrasensitive cavity-enhanced frequency modulation spectroscopy of a C(2)HD overtone transition.

Using our cavity-enhanced frequency modulation technique, we obtained the saturated signal of the weakly absorbing gas C(2)HD for the P(5) line of the (nu(2) + 3nu(3)) overtone band at 1.064 microm. An absorption sensitivity of 1.2 x 10(-10) (1.8 x 10(-12)/cm) has been obtained. The absolute frequency of the line center is established (within +/-2.6 kHz) with respect to a doubled Nd:YAG laser/I(2) frequency reference. The short-term stability, limited by the available signal-to-noise ratio, currently is 1 + 10(-11) at 1 s, improving to 5 x 10(-13) at 1000 s. The measured pressure-broadening rate is 34.7(0.8) kHz/mTorr (260 +/- 6.1 kHz/Pa). Selection of slow molecules gave a linewidth four times narrower than the room-temperature transit-time limit.

Delivering the same optical frequency at two places: accurate cancellation of phase noise introduced by an optical fiber or other time-varying path.

Although a single-mode optical fiber is a convenient and efficient interface/connecting medium, it introduces phase-noise modulation, which corrupts high-precision frequency-based applications by broadening the spectrum toward the kilohertz domain. We describe a simple double-pass fiber noise measurement and control system, which is demonstrated to provide millihertz accuracy of noise cancellation.