Establishing an experimental rat model of photodynamically-induced retinal vein occlusion using erythrosin B

AIM

To develop a reliable, reproducible rat model of retinal vein occlusion (RVO) with a novel photosensitizer (erythrosin B) and study the cellular responses in the retina.

METHODS

Central and branch RVOs were created in adult male rats via photochemically-induced ischemia. Retinal changes were monitored via color fundus photography and fluorescein angiography at 1 and 3h, and 1, 4, 7, 14, and 21d after irradiation. Tissue slices were evaluated histopathologically. Retinal ganglion cell survival at different times after RVO induction was quantified by nuclear density count. Retinal thickness was also observed.

RESULTS

For all rats in both the central and branch RVO groups, blood flow ceased immediately after laser irradiation and retinal edema was evident at one hour. The retinal detachment rate was 100% at 3h and developed into bullous retinal detachment within 24h. Retinal hemorrhages were not observed until 24h. Clearance of the occluded veins at 7d was observed by fluorescein angiography. Disease manifestation in the central RVO eyes was more severe than in the branch RVO group. A remarkable reduction in the ganglion cell count and retinal thickness was observed in the central RVO group by 21d, whereas moderate changes occurred in the branch RVO group.

CONCLUSION

Rat RVO created by photochemically-induced ischemia using erythrosin B is a reproducible and reliable animal model for mimicking the key features of human RVO. However, considering the 100% rate of retinal detachment, this animal model is more suitable for studying RVO with chronic retinal detachment.

Protein and miRNA profiling of radiation-induced skin injury in rats: the protective role of peroxiredoxin-6 against ionizing radiation

Radiation-induced skin injury is a serious concern during radiotherapy. However, the molecular mechanism underlying the pathogenesis of radiation-induced skin injury has not been extensively reported. Most biological functions are performed and regulated by proteins and noncoding RNAs, including microRNAs (miRNAs). The interplay between mRNA and miRNA has been implicated in disease initiation and progression. Technical advances in genomics and proteomics have enabled the exploration of the etiology of diseases and have the potential to broaden our understanding of the molecular pathogenesis of radiation-induced skin injury. In this study, we compared the protein and miRNA expression in rat skin irradiated with a 45-Gy electron beam with expression from adjacent normal tissues. We found 24 preferentially expressed proteins and 12 dysregulated miRNAs in irradiated skin. By analyzing the protein and miRNA profiles using bioinformatics tools, we identified a possible interaction between miR-214 and peroxiredoxin-6 (PRDX-6). Next, we investigated the expression of PRDX-6 and the consequences of its dysregulation. PRDX-6 is suppressed by radiation-inducible miR-214 and is involved in the pathogenesis of radiation-induced skin injury. Overexpression of PRDX-6 conferred radioresistance on cells, decreased cell apoptosis, and preserved mitochondrial integrity after radiation exposure. In addition, in vivo transfection with PRDX-6 reduced radiation-induced reactive oxygen species and the malondialdehyde concentration and ameliorated radiation-induced skin damage in rats. Our present findings illustrate the molecular changes during radiation-induced skin injury and the important role of PRDX-6 in ameliorating this damage in rats.

MicroRNA-93 inhibits inflammatory cytokine production in LPS-stimulated murine macrophages by targeting IRAK4

Endotoxin-induced uveitis (EIU) is an animal model of acute ocular inflammation for the study of human endogenous anterior uveitis. The mechanisms accounting for the development of ocular inflammation remain hazy. MicroRNAs (mi-RNAs) have been proposed as novel regulators of inflammation. It remains unclear whether a microRNA-mediated regulatory mechanism is involved in LPS-induced EIU. In this study, we report that miR-93 expression in the eyes of EIU rats and LPS-stimulated macrophages is significantly decreased. We also show that miR-93 inhibits NF-κB activation and pro-inflammatory cytokines by targeting IRAK4 expression. We further demonstrate that miR-93 inhibits IRAK4 expression by binding directly to the 3'-UTR of IRAK4. Our findings suggest that miR-93 is a negative regulator of the immune response in EIU.

[Study on the correlation between serum lipid and serum carnitine palmitoyl transferase 1A in rural adults over 40 years in Tianjin]

OBJECTIVE

To explore the status of serum lipids and analyze its relationship with carnitine palmitoyl transferase 1A (CPT1 A) in rural people over 40 in Tianjin, China.

METHODS

By cluster multi-stratified sample of 719 people over 40 was investigated with a questionnaire from rural areas in Tianjin. And finally draw a conclusion based on data analysis from fasting blood and measured total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C) and CPT1 A.

RESULTS

In this research, the rate of dyslipidemia was 46.73%, in which 48.22 percent male and 45.41 percent female, a nonsignificant difference. CPT1 A correlated with TC, LDL-C were 0.123 and 0.130, with simple linear regression, and there was only significant difference between LDL-C and CPT1 A by multiple regression analysis.

CONCLUSION

There is a high rate of dyslipidemia among the rural people over the age of 40 in Tianjin, and the CPT1 A is closely associated with serum lipid.

HIV-TAT mediated protein transduction of heme oxygenase-1 protects HaCaT cells from ionizing radiation

OBJECTIVE

To elucidate the effects of human keratinocyte-derived HaCaT cells (HIV-TAT) protein transduction domains (PTD) coupled heme oxygenase-1 (HO-1) fusion protein (TAT-HO-1) on radiation-induced human keratinocyte-derived HaCaT cells.

METHODS

This study was conducted between May 2010 and February 2013 in the School of Radiation Medicine and Protection, Soochow University, Suzhou, China. This experimental study was designed to explore the protective role of TAT-HO-1 in skin cells. The human HO-1 gene was fused with a gene fragment encoding TAT PTD to produce in-frame TAT-HO-1. The distribution of TAT-HO-1 was measured by immunostaining and Western blot. The radioprotection for TAT-HO-1 was determined using clonogenic assay. Alterations in apoptosis were analyzed by flow cytometry.

RESULTS

The expressed and purified TAT-HO-1 recombinant protein could be incorporated into human HaCaT cells. We then evaluated the protective role of TAT-HO-1 against ionizing radiation. The TAT-HO-1 attenuated the generation of reactive oxygen species and decreased HaCaT cell radiosensitivity to irradiation. Moreover, HaCaT cells pretreated with TAT-HO-1 resulted in less apoptosis by radiation. In addition, TAT-HO-1 could penetrate rat skin.

CONCLUSION

These results suggest that TAT-HO-1 can protect HaCaT cells from ionizing radiation.

Effect of aerobic exercise and low carbohydrate diet on pre-diabetic non-alcoholic fatty liver disease in postmenopausal women and middle aged men--the role of gut microbiota composition: study protocol for the AELC randomized controlled trial

Background

Pre-diabetes and non-alcoholic fatty liver disease (NAFLD) are associated with an unhealthy lifestyle and pose extremely high costs to the healthcare system. In this study, we aim to explore whether individualized aerobic exercise (AEx) and low carbohydrate diet (LCh) intervention affect hepatic fat content (HFC) in pre-diabetes via modification of gut microbiota composition and other post-interventional effects.

Methods/design

A 6-month randomized intervention with 6-month follow-up is conducted from January 2013 to December 2015. The target sample size for intervention is 200 postmenopausal women and middle-aged men aged 50–65 year-old with pre-diabetes and NAFLD. The qualified subjects are randomized into 4 groups with 50 subjects in each group: 1 = AEx, 2 = LCh, 3 = AEx + LCh, and 4 = control. In addition, two age-matched reference groups (5 = pre-diabetes without NAFLD (n = 50) and 6 = Healthy without pre-diabetes or NAFLD (n = 50)) are included. The exercise program consists of progressive and variable aerobic exercise (intensity of 60 to 75% of initial fitness level, 3–5 times/week and 30–60 min/time). The diet program includes dietary consultation plus supplementation with a special lunch meal (40% of total energy intake/day) which aims to reduce the amount of carbohydrate consumption (30%). The control and reference groups are advised to maintain their habitual habits during the intervention. The primary outcome measures are HFC, serum metabolomics and gut microbiota composition. The secondary outcome measures include body composition and cytokines. In addition, socio-psychological aspects, social support, physical activity and diet will be performed by means of questionnaire and interview.

Discussion

Specific individualized exercise and diet intervention in this study offers a more efficient approach for liver fat reduction and diabetes prevention via modification of gut microbiota composition. Besides, the study explores the importance of incorporating fitness assessment and exercise in the management of patients with pre-diabetes and fatty liver disorders. If our program is shown to be effective, it will open new strategies to combat these chronic diseases.

Trial registration

Current Controlled Trials: ISRCTN42622771.

Amelioration of radiation-induced skin injury by HIV-TAT-mediated protein transduction of RP-1 from Rana pleurade

Radiation-induced reactive oxygen species (ROS) can damage DNA and most other biological macromolecules in skin and radiation-induced skin injury is a serious concern for radiation therapy. Skin possesses an extremely efficient antioxidant system, which is conferred by two systems: antioxidant enzymes and small molecules that can scavenge ROS by donating electrons. Amphibian skin is a multifunctional organ, which protects against dangers of various oxidative stresses. Recently, a small peptide called RP-1 was isolated from the skin secretions of Rana pleurade, which shows strong antioxidant activity. However, this RP-1 peptide is limited because its inability to across the cell membrane. Protein transduction domains (PTDs) have demonstrated high efficiency for facilitating the internalization of both homologous and heterogeneous proteins into cells. This study aims to elucidate the protective effects of a HIV-TAT (TAT) PTD-coupled RP-1 fusion protein (TAT-RP1) on radiation-induced skin injury in vitro and in vivo. The synthesized fusion TAT-RP1 peptide can be incorporated into human keratinocyte HaCaT cells in a dose- and time-dependent manner without cytotoxicity. We then evaluated the protective role of TAT-RP1 against ionizing radiation. TAT-RP1 supplementation increased anti-superoxide anion ability of HaCaT cells and decreased HaCaT cell radiosensitivity to irradiation. Moreover, TAT-RP1 was able to penetrate the skin of rats, entering epidermis as well as the dermis of the subcutaneous layer in skin tissue. Topical spread of TAT-RP1 promoted the amelioration of radiation-induced skin damage in rats. These results suggest that TAT-RP1 has potential as a protein therapy for radiation-induced skin injury.

Mutational analysis of positively charged residues in the N-terminal region of the class IIa bacteriocin pediocin PA-1

The significance of positively charged residues for the target cell binding of pediocin PA-1 bacteriocins was studied by site-directed mutagenesis. Most of the charged residues are located in the N-terminal half of the peptide, which is thought to mediate the initial binding of these bacteriocins to their target cells through electrostatic interactions. Mutated peptides in which the positively charged residues were substituted or increased in number were constructed, and some of these peptides exhibited a twofold increase in the bacteriostatic activity. The greatest enhancement was achieved by introduced the positive charges at position 13, their results show the benefits of introducing an additional cationic residue within this patch in the middle of the N-terminal half of pediocin PA-1 bacteriocins. Thus, the presence of additional cationic residues in the N-terminal half influenced the electrostatic binding of this bacteriocin to its target cells and increased the potency of the peptide on the potency of Micrococcus luteus and Staphylococcus aureus.

SIGNIFICANCE AND IMPACT OF THE STUDY

No previous work has systematically examined the N-terminal cationic residues of the pediocin PA-1 for their functional importance or redundancy. In this study, we examined the structure-function relationships of pediocin PA-1 by site-directed mutagenesis. Mutated peptides in which the positively charged residues were substituted and increased in number exhibited a twofold increase in the bacteriostatic activity. This study demonstrated the importance of the cationic patch in the N-terminal half of pediocin PA-1. The cationic residues influenced the electrostatic binding of the bacteriocin to the target cells and had a greater effect on the potency of the peptide towards Micrococcus luteus and Staphylococcus aureus.

Carrier saturation in multiple quantum well metallo-dielectric semiconductor nanolaser: is bulk material a better choice for gain media?

Although multi quantum well (MQW) structure is frequently suggested as the appropriate medium for providing optical gain in nanolasers with low threshold current, we demonstrate that in general bulk gain medium can be a better choice. We show that the high threshold gain required for nanolasers demands high threshold carrier concentrations and therefore a highly degenerate condition in which the barriers between the quantum wells are heavily pumped. As a result, there occurs spontaneous emission from the barrier in very dissipative low Q modes or undesired confined higher Q modes with resonance wavelengths close to the barrier bandgap. This results in a competition between wells and barriers that suppresses lasing. A complete model involving the optical properties of the resonant cavity combined with the carrier injection in the multilayer structure is presented to support our argument. With this theoretical model we show that while lasing is achieved in the nanolaser with bulk gain media, the nanolaser with MQW gain structure exhibits well emission saturation due to the onset of barrier emission.

HIV-TAT mediated protein transduction of Cu/Zn-superoxide dismutase-1 (SOD1) protects skin cells from ionizing radiation

Background

Radiation-induced skin injury remains a serious concern during radiotherapy. Cu/Zn-superoxide dismutase (Cu/Zn-SOD, SOD₁) is a conserved enzyme for scavenging superoxide radical in cells. Because of the integrity of cell membranes, exogenous molecule is not able to be incorporated into cells, which limited the application of natural SOD₁. The aim of this study was to evaluate the protective role of HIV-TAT protein transduction domain mediated protein transduction of SOD₁ (TAT-SOD₁) against ionizing radiation.

Methods

The recombinant TAT-SOD₁ and SOD₁ were obtained by prokaryotic–based protein expression system. The transduction effect and biological activity of TAT-SOD₁ was measured by immunofluorescence and antioxidant capability assays in human keratinocyte HaCaT cells. Mito-Tracker staining, reactive oxygen species (ROS) generation assay, cell apoptosis analysis and malondialdehyde (MDA) assay were used to access the protective effect of TAT- SOD₁.

Results

Uptake of TAT-SOD₁ by HaCaT cells retained its biological activity. Compared with natural SOD₁, the application of TAT-SOD₁ significantly enhanced the viability and decreased the apoptosis induced by X-ray irradiation. Moreover, TAT-SOD₁ reduced ROS and preserved mitochondrial integrity after radiation exposure in HaCaT cells. Radiation-induced γH2AX foci, which are representative of DNA double strand breaks, were decreased by pretreatment with TAT-SOD₁. Furthermore, subcutaneous application of TAT-SOD₁ resulted in a significant decrease in 45 Gy electron beam-induced ROS and MDA concentration in the skins of rats.

Conclusions

This study provides evidences for the protective role of TAT-SOD₁ in alleviating radiation-induced damage in HaCaT cells and rat skins, which suggests a new therapeutic strategy for radiation-induced skin injury.

Codon optimisation improves the expression of Trichoderma viride sp. endochitinase in Pichia pastoris

The mature cDNA of endochitinase from Trichoderma viride sp. was optimised based on the codon bias of Pichia pastoris GS115 and synthesised by successive PCR; the sequence was then transformed into P. pastoris GS115 via electroporation. The transformant with the fastest growth rate on YPD plates containing 4 mg/mL G418 was screened and identified. This transformant produced 23.09 U/mL of the recombinant endochitinase, a 35% increase compared to the original strain bearing the wild-type endochitinase cDNA. The recombinant endochitinase was sequentially purified by ammonia sulphate precipitation, DE-52 anion-exchange chromatography and Sephadex G-100 size-exclusion chromatography. Thin-layer chromatography indicated that the purified endochitinase could hydrolyse chito-oligomers or colloidal chitin to generate diacetyl-chitobiose (GlcNAc)₂ as the main product. This study demonstrates (1) a means for high expression of Trichoderma viride sp. endochitinase in P. pastoris using codon optimisation and (2) the preparation of chito-oligomers using endochitinase.

A specific genomic organization and a novel promoter sequence for both ZP2 and ZP3 gene expressions in the Pingxiang red transparent crucian carp, Carassius auratus var. pingxiangnensis

We cloned the full-length cDNA of ZP2 from Carassius auratus var. Pingxiangnensis (CaP_ZP2) and identified a cluster of three ZP genes through its DNA walker. These three genes, CaP_ZP3.1, CaP_ZP2 and CaP_ZP3.2 were located within a 10,855bp region and each comprised of eight exons spanning 1348bp, 1638bp and 1348bp, respectively. Protein bands of egg membrane between 40 and 70kDa were in concordance with the deduced amino acid of these three CaP_ZP genes cDNA and with their molecular mass. This is the first report that two CaP_ZP3 genes were separated by CaP_ZP2 gene. A novel sequence of 1097bp, located between CaP_ZP2 and CaP_ZP3.2, was inserted into the modified pAcGFP1-1 vector in the forward and reverse directions. Results showed that individual sequence served as promoters utilizing common regulatory elements in the forward and reverse directions for both CaP_ZP2 and CaP_ZP3.2 gene expressions. In situ hybridization against CaP_ZP2 confirmed that a strong positive signal was detected in the early development oocytes. Similarly, real-time PCR results also showed that CaP_ZP2 transcription increased mainly in a 4-8month ovary, but was decreased dramatically in a 9-12month ovary.

Prostanoid therapy for pulmonary arterial hypertension: a meta-analysis of survival outcomes

BACKGROUND

Prostanoids have played an important role in the treatment of pulmonary arterial hypertension (PAH). However, whether prostanoid therapy provides a survival advantage is still not clear. The aim of this meta-analysis was to evaluate the efficacy and safety of prostanoids in PAH, focusing on the improvement in overall survival.

METHODS

Trials were identified from the Cochrane Library, EMBASE, and PUBMED databases. We calculated risk ratios (RR) for dichotomous data and weighted mean differences with 95 % confidence intervals (CI) for continuous data.

RESULTS

Fourteen trials with a total of 2,244 adult patients (1,189 patients in the prostanoid treatment group and 1,055 patients in the placebo group) were included in the meta-analysis. All-cause mortality rate in the control group was 4.17 %. In a 13.4-week follow-up, prostanoid treatment was associated with a 44 % reduction in mortality (RR 0.56; 95 % CI 0.35-0.88; P = 0.01).Subgroup analysis suggested that only treatment with intravenous prostanoids provided a survival benefit. Compared with placebo, prostanoids significantly reduced clinical worsening (RR 0.60; 95 % CI 0.46-0.80; P = 0.0003), increased the 6-min walk distance by 27.95 m, reduced mean pulmonary arterial pressure and pulmonary vascular resistance, and increased the cardiac index and mixed venous oxygen saturation. However, patients receiving prostanoid treatment showed a much higher incidence (RR 3.25; 95 % CI 2.07-5.10; P<0.00001) of withdrawal due to its adverse effects.

CONCLUSION

The results of this meta-analysis suggest that treatment with prostanoids improves the survival of patients with PAH.

Echocardiographic parameters in patients with pulmonary arterial hypertension: correlations with right ventricular ejection fraction derived from cardiac magnetic resonance and hemodynamics

BACKGROUND

Echocardiography is the most convenient method used to evaluate right ventricular function, and several echocardiographic parameters were studied in previous studies. But the value of these parameters to assess the right ventricular function in patients with pulmonary arterial hypertension (PAH) has not been well defined.

METHODS

Patients with PAH were observed prospectively. Right heart catheterization, echocardiography and cardiac magnetic resonance (CMR) were performed within 1 week interval. The correlations between echocardiographic parameters and right ventricular ejection fraction (RVEF) derived from CMR as well as hemodynamics were analyzed.

RESULTS

Thirty patients were enrolled including 24 with idiopathic PAH, 5 with PAH associated with connective tissue diseases and 1 with hereditary PAH. All echocardiographic parameters except right ventricular myocardial performance index (RVMPI) correlated significantly with RVEF (tricuspid annual plane systolic excursion [TAPSE], r = 0.440, P = 0.015; tricuspid annular systolic excursion velocity [S'], r = 0.444, P = 0.016; isovolumic acceleration [IVA], r = 0.600, P = 0.001; right ventricular fraction area change [RVFAC], r = 0.416, P = 0.022; ratio of right ventricular transverse diameter to left ventricular transverse diameter [RVETD/LVETD], r = -0.649, P<0.001; RVMPI, r = -0.027, P = 0.888). After adjusted for mean right atrial pressure, mean pulmonary arterial pressure and pulmonary vascular resistance (PVR), only IVA and RVETD/LVETD could independently predict RVEF. Four echocardiographic parameters displayed significant correlations with PVR (TAPSE, r = -0.615, P<0.001; S', r = -0.557, P = 0.002; RVFAC, r = -0.454, P = 0.012; RVETD/LVETD, r = 0.543, P = 0.002).

CONCLUSIONS

The echocardiographic parameters IVA and RVETD/LVETD can reflect RVEF independently regardless of hemodynamics in patients with PAH. In addition, TAPSE, S', RVFAC and RVETD/LVETD can also reflect PVR in PAH patients.

A case of endoscopic ultrasound diagnosis of gastric amyloidosis

A 37-year-old female presented to our hospital with the complaint of abdominal distension for one month. A gastroscopy examination showed extensive chyme retention and varying erosion and ulceration of the gastric body. The pathology showed moderate chronic inflammation and erosion of the gastric body mucosa, with accompanying Helicobacter pylori infection. She accepted treatment for one month. The patient then accepted to undergo endoscopic ultrasonography, which showed that normal structure of the gastric body intumescence was discernible. The pathology showed chronic mild-moderate inflammation of the gastric body mucosa associated with interstitial amyloidosis, with accompanying Helicobacter pylori infection. She accepted treatment for the eradication of Helicobacter pylori, and the original ulcer healed.

Purcell effect in sub-wavelength semiconductor lasers

We present a formal treatment of the modification of spontaneous emission rate by a cavity (Purcell effect) in sub-wavelength semiconductor lasers. To explicitly express the assumptions upon which our formalism builds, we summarize the results of non-relativistic quantum electrodynamics (QED) and the emitter-field-reservoir model in the quantum theory of damping. Within this model, the emitter-field interaction is modified to the extent that the field mode is modified by its environment. We show that the Purcell factor expressions frequently encountered in the literature are recovered only in the hypothetical condition when the gain medium is replaced by a transparent medium. Further, we argue that to accurately evaluate the Purcell effect, both the passive cavity boundary and the collective effect of all emitters must be included as part of the mode environment.

[Clinical observation of cardiopulmonary exercise test in patients with idiopathic pulmonary arterial hypertension]

OBJECTIVE

To explore the exercise characteristics of patients with idiopathic pulmonary arterial hypertension (IPAH).

METHODS

From November 2010 to September 2012 , 76 consecutive IPAH patients and 24 healthy controls from Fuwai Cardiovascular Hospital were enrolled to undergo cardiopulmonary exercise testing. The exercise parameters were compared. Correlations among peak oxygen consumption, anaerobic threshold, peak oxygen pulse, New York Heart Association (NYHA) class, N-terminal pro-brain natriuretic peptide (NT-proBNP), 6-minute walking distance (6 MWD) and cardiac index are analyzed in IPAH.

RESULTS

There were 21 males and 55 females in IPAH and 8 males and 16 females in controls. Their mean ages were (31.5 ± 10.6) and (35.5 ± 6.4) years respectively. Significant differences (P = 0.000) existed between two groups in peak oxygen consumption ((12.7 ± 3.3) vs (25.6 ± 5.8) ml·min(-1)·kg(-1)), anaerobic threshold ((9.8 ± 2.5) vs (16.7 ± 3.9) ml·min(-1)·kg(-1)), peak oxygen pulse ((5.3 ± 1.6) vs (9.9 ± 2.5) ml/bpm) and ventilator efficiency (slope of minute ventilation in relation to CO2 produced) ((42.6 ± 2.0) vs (25.5 ± 3.5)). In IPAH, peak oxygen consumption was significantly correlated with NYHA class (r = -0.509, P = 0.000), 6 MWD (r = 0.443, P = 0.002) and NT-proBNP levels (r = -0.423, P = 0.011). And anaerobic threshold was significantly correlated with NYHA class (r = -0.362, P = 0.002), 6MWD (r = 0.343, P = 0.004) and NT-proBNP levels (r = -0.275, P = 0.017). Peak oxygen pulse and ventilator efficiency were both correlated well with total pulmonary vascular resistance. Partial correlation analysis demonstrated that there were significant correlations among peak oxygen consumption, anaerobic threshold, NYHA class, NT-proBNP levels and 6MWD after adjusting for age, gender and weight.

CONCLUSIONS

Peak oxygen consumption and anaerobic threshold decrease ventilator efficiency in IPAH patients. Cardiopulmonary exercise testing is an invasive tool of assessing safely the function of IPAH patients.