Selective area growth of AlN/GaN nanocolumns on (0001) and (11-22) GaN/sapphire for semi-polar and non-polar AlN pseudo-templates.

Despite the strong interest in optoelectronic devices working in the deep ultraviolet range, no suitable low cost, large-area, high-quality AlN substrates have been available up to now. The aim of this work is the selective area growth of AlN nanocolumns by plasma assisted molecular beam epitaxy on polar (0001) and semi-polar (11-22) GaN/sapphire templates. The resulting AlN nanocolumns are vertically oriented with semi-polar {1-103} top facets when grown on (0001) GaN/sapphire, or oriented at 58° from the template normal and exposing {1-100} non-polar top facets when growing on (11-22) GaN/sapphire, in both cases reaching filling factors ≥80%. In these kinds of arrays each nanostructure could function as a building block for an individual nano-device or, due to the large filling factor values, the overall array top surfaces could be seen as a quasi (semi-polar or non-polar) AlN pseudo-template.

Impacts of ambient temperature on the burden of bacillary dysentery in urban and rural Hefei, China.

Bacillary dysentery continues to be a major health issue in developing countries and ambient temperature is a possible environmental determinant. However, evidence about the risk of bacillary dysentery attributable to ambient temperature under climate change scenarios is scarce. We examined the attributable fraction (AF) of temperature-related bacillary dysentery in urban and rural Hefei, China during 2006-2012 and projected its shifting pattern under climate change scenarios using a distributed lag non-linear model. The risk of bacillary dysentery increased with the temperature rise above a threshold (18·4 °C), and the temperature effects appeared to be acute. The proportion of bacillary dysentery attributable to hot temperatures was 18·74% (95 empirical confidence interval (eCI): 8·36-27·44%). Apparent difference of AF was observed between urban and rural areas, with AF varying from 26·87% (95% eCI 16·21-36·68%) in urban area to -1·90% (95 eCI -25·03 to 16·05%) in rural area. Under the climate change scenarios alone (1-4 °C rise), the AF from extreme hot temperatures (>31·2 °C) would rise greatly accompanied by the relatively stable AF from moderate hot temperatures (18·4-31·2 °C). If climate change proceeds, urban area may be more likely to suffer from rapidly increasing burden of disease from extreme hot temperatures in the absence of effective mitigation and adaptation strategies.

Effect of diurnal temperature range on the outpatient visits for acute bronchitis in children: a time-series study in Hefei, China.

OBJECTIVES: To determine the relationship between diurnal temperature range (DTR) and outpatient visits for childhood acute bronchitis (AB) in Hefei, China, to analyze whether DTR effect was delayed, and to explore the susceptible populations. STUDY DESIGN: An ecological study. METHODS: A Poisson generalized linear regression model combined with a distributed lag non-linear model was used to analyze the relationship between DTR and childhood AB from Hefei, China during 2010-2013, after adjusting for long-term trend and seasonality, mean temperature and relative humidity. RESULTS: An adverse effect of DTR on childhood AB was observed, and the impact of DTR was greatest at three days lag, with a 1.0% (95% confidence interval = 0.5-1.6%) increase of AB cases per 1 °C increment of DTR. Female children and children aged 0-4 years appeared to be more vulnerable to DTR effect than other children. CONCLUSIONS: Our study suggests that large DTR may increase the incidence of childhood AB in Hefei, particularly for those who are female and young. Caregivers and health practitioners should be made aware of the potential threat posed by large DTR.

[Numerical simulation modeling of middle ear-eustachian tube ventilation based on Chinese digital visual human body].

Objective: To establish a three-dimensional model of middle ear-eustachian tube based on Chinese digital visual human dataset, and the deformation and pressure changes of the middle ear-eustachian tube system after eustachian tube opening are simulated by computer numerical simulation. Methods: The first female Chinese Digital Visual Human data was adopted. The images were imported by Amira image processing software, and the images were segmented by Geomagic software to form a three-dimensional model of middle ear-eustachian tube system, including eustachian tube, tympanum, tympanic membrane, auditory ossicles, and mastoid air cells system. The 3D model was imported into Hypermesh software for meshing and analysis. The structural mechanics calculation was carried out by Abaqus, and gas flow was simulated by Xflow. The tissue deformation and middle ear pressure changes during eustachian tube opening were numerically simulated by fluid-solid coupling algorithm. Several pressure monitoring points including tympanum, mastoid, tympanic isthmus, and external auditory canal were set up in the model, and the pressure changes of each monitoring point were recorded and compared. Results: In this study, a three-dimensional model of middle ear-eustachian tube and a numerical simulation model of middle ear ventilation were established, including eustachian tube, tympanum, mastoid air cells, tympanic membrane, and auditory ossicles. The dynamic changes of the model after ventilation could be divided into five stages according to the pressure. In addition, the pressure changes of tympanum and tympanic isthmus were basically synchronous, and the pressure changes of mastoid air cells system were later than that of tympanum and tympanic isthmus, which verified the pressure buffering effect of mastoid. The extracted pressure curve of the external auditory canal was basically consistent with that of tympanometry in terms of value and trend, which verified the effectiveness of the model. Conclusions: The numerical simulation model of middle ear-eustachian tube ventilation established in this paper can simulate the tissue deformation and middle ear pressure changes after eustachian tube opening, and its accuracy and effectiveness are also verified. This not only lays a foundation for further research, but also provides a new research method for the study of middle ear ventilation.

Dietary supplementation with Chinese herbal powder enhances ileal digestibilities and serum concentrations of amino acids in young pigs.

This study was designed to determine the effect of ultra-fine Chinese herbal powder as a dietary additive on serum concentrations and apparent ileal digestibilities (AID) of amino acids (AA) in young pigs. In Experiment 1, 60 Duroc x Landrace x Yorkshire piglets weaned at 21 days of age were randomly assigned to one of three treatments, representing supplementation with 0 or 2 g/kg of the powder, or 0.2 g/kg of colistin (an antibiotic) to corn- and soybean meal-based diets (n = 20 per group). Blood samples from five piglets per group were collected on days 7, 14, and 28 to determine serum AA concentrations. In Experiment 2, 12 barrows with an average initial body weight of 7.64 kg were randomly assigned to one of the three dietary treatments, followed by surgical placement of a simple T-cannula at the terminal ileum. All of the diets contained 0.1% titanium oxide as a digestibility marker. The samples of terminal ileal digesta were collected on day 7 for determining AID of AA. Results show that dietary supplementation with the herbal powder increased (P < 0.05) serum concentrations and AID of most AA by 10-50% and 10-16%, respectively. As an indicator of improved intestinal function, AID values of calcium were also enhanced in piglets supplemented with the herbal powder. Dietary supplementation of colistin increased serum concentrations and AID values of some AA by 8-44% and 10-15%, respectively, in comparison with the non-supplemented group. These novel findings demonstrate that the herbal powder can enhance the digestibility of dietary protein and the intestinal absorption of AA into the systemic circulation in post-weaning pigs, therefore providing a new mechanism for its growth- and immunity-promoting efficacy.

Orexin A promotes granulosa cell secretion of progesterone in sheep.

BACKGROUND: Orexin A, a small-molecule peptide, can regulate female hormones, but limited evidence for its mechanism of activity exists in ovine. AIMS: The objective of this study was to investigate the effect of orexin A on progesterone (P4) secretion in cultured granulosa of sheep follicles. METHODS: Sheep ovarian granulosa were isolated and identified, pre-incubated with luteinizing hormone (LH) (2.5 IU/ml), follicle-stimulating hormone (FSH) (2.5 IU/ml), or oestrogen (1 µg/ml); and cultured in vitro. The pretreated sheep ovarian granulosa were subsequently cultured with different concentrations (1 nM, 10 nM, 58 nM, 100 nM, and 145 nM) of orexin A for varying amounts of time (0 h, 24 h, 48 h, and 72 h). Then, the expression levels of P4, steroidogenic acute regulatory protein (StAR), 3ß-Hydroxysteroid dehydrogenase (3ß-HSD) and cytochrome P450 (CYP11) were determined. RESULTS: The results showed that the sheep ovarian granulosa were correctly identified. The different concentrations of orexin A promoted the secretion of P4 from granulosa in the ovine ovary compared with that in the control. The expression of StAR, 3ß-HSD and P450 (CYP11) gradually increased, and then decreased with increasing concentrations of orexin A, but the expression of P450 (CYP11) decreased with the increase of time. CONCLUSION: These results revealed that orexin A promotes the secretion of P4 by regulating the expression of StAR, 3ß-HSD, and P450 (CYP11). Understanding the mechanism underlying the promotion of P4 by orexin A could open new therapeutic possibilities in the treatment of hormone homeostasis.

[Influence of humidex on incidence of bacillary dysentery in Hefei: a time-series study].

Objective: To investigate the effect of humidex combined with mean temperature and relative humidity on the incidence of bacillary dysentery in Hefei. Methods: Daily counts of bacillary dysentery cases and weather data in Hefei were collected from January 1, 2006 to December 31, 2013. Then, the humidex was calculated from temperature and relative humidity. A Poisson generalized linear regression combined with distributed lag non-linear model was applied to analyze the relationship between humidex and the incidence of bacillary dysentery, after adjusting for long-term and seasonal trends, day of week and other weather confounders. Stratified analyses by gender, age and address were also conducted. Results: The risk of bacillary dysentery increased with the rise of humidex. The adverse effect of high humidex (90 percentile of humidex) appeared in 2-days lag and it was the largest at 4-days lag (RR=1.063, 95%CI: 1.037-1.090). Subgroup analyses indicated that all groups were affected by high humidex at lag 2-5 days. Conclusion: High humidex could significantly increase the risk of bacillary dysentery, and the lagged effects were observed.

Assessment of myocardial segmental function with coronary artery stenosis in multi-vessel coronary disease patients with normal wall motion.

OBJECTIVE: To discover the impact of the various degrees of coronary artery stenosis (CAD) on the left ventricular systolic dysfunction in steady state with quantitative analysis of the regional systolic myocardium in longitudinal, radial and circumferential direction in patients with coronary artery disease by two-dimensional speckle tracking imaging (STI). PATIENTS AND METHODS: Forty-three normal wall motion-multi vessel coronary artery disease (NWM-MVD) patients labeled as the experimental groups and forty-two subjects with little risk of CAD marked as the control group were enrolled in this study. The two-dimensional STI was obtained in the apical long axis and three levels of the short axis of the left ventricle. The left ventricular wall was divided into 18 segments. The affected myocardia were divided into three groups: group B (coronary stenosis degree ≤50%), group C (coronary stenosis degree 50%-99%)and group D (coronary stenosis degree ≥99%). Using the Q-analysis software, the longitudinal, radial and circumferential systolic strain (SL, SR, SC) and strain ratio (SrL, SrR, SrC) of the myocardium were analyzed. RESULTS: The bradycardia in the NWM-MVD group is greater than that in the control group (16/43 vs. 7/42, p <0.05). Compared with the control group, the SL and SR of group B, group C and group D decreased significantly (p <0.05). Compared with group C, the SL of group D also decreased significantly (p <0.05). However, there was no SC difference among the four groups. Meanwhile, compared with group A, the SrL, SrR and SrC of group B, group C and group D decreased significantly (p <0.05). Compared with group A, group B and group C, the SrL and SrC of group D also decreased (p <0.05). Compared with group A and group C, the SrR of group D decreased. The SrL was equal to 1.085 for the cut-off value, and the sum (1.348) of sensitivity (0.673) and specificity (0.675) were the greatest. Bland-Altman analysis showed that there was myocardium conformity of in both the multi-vessel CAD patients and the control subjects. CONCLUSIONS: Myocardial systolic function was impaired in the MVD patients of group B (coronary stenosis degree ≤50%), group C (coronary stenosis degree 50%-99%)and group D (coronary stenosis degree ≥99%), especially the longitudinal and radial systolic function, even though they had normal wall motion. The SrL equaled 1.085 for the cut-off value, and the sums (1.348) of sensitivity (0.673) and specificity (0.675) were the greatest. Bradycardia might be a compensatory mechanism in NWM-MVD patients.

Assessment of the left ventricular systolic function in multi-vessel coronary artery disease with normal wall motion by two-dimensional speckle tracking echocardiography.

OBJECTIVE: To evaluate the clinical value of two-dimensional speckle tracking echocardiography for analyzing the left ventricular systolic function in patients with multi-vessel coronary artery disease with normal wall motion (NWM-MVD). PATIENTS AND METHODS: Forty-five NWM-MVD patients and thirty-six subjects with low risk of coronary artery disease (control group) were enrolled in this study. Echocardiogram images of the short axis of the left ventricle and apical long axis were obtained. The Q-analysis software was used to analyze the peak systolic strain of the left ventricular segments and the global longitudinal strain (GLS). We calculated the left ventricular global circumferential strain (GCS) and the radial strain (GRS), as well as the longitudinal, radial and circumferential strain of the basal (Bas-GLS, Bas-GCS, Bas-GRS), middle (Mid-GLS, Mid-GCS, Mid-GRS) and apical segments (Ap-GLS, Ap-GCS, Ap-GRS). RESULTS: (1) The coronary occlusion or subtotal occlusion were visible in 85.71% of the NWM-MVD patients. (2) The heart rate of the NWM-MVD patients was lower than that of the control group [(61.78 ± 6.76) beats/min vs. (66.13 ± 6.24) beats/min, p < 0.05]. The conventional ultrasonic measurement indices are similar between the NWM-MVD group and the control group (p > 0.05). (3) Compared with the control group, the GLS, Bas-GLS, Mid-GLS, Bas-GCS, Mid-GCS, GRS and Bas-GRS were lower in the NWM-MVD group (p < 0.05). CONCLUSIONS: The longitudinal, circumferential and radial systolic functions of the NWM-MVD patients were impaired at different degrees.

Structure, mechanical property and corrosion behaviors of (HA+ß-TCP)/Mg-5Sn composite with interpenetrating networks.

In this paper, a novel (Hydroxyapatite+ß-tricalcium phosphate)/Mg-5Sn ((HA+ß-TCP)/Mg-5Sn) composite with interpenetrating networks was fabricated by infiltrating Mg-5Sn alloy into porous HA+ß-TCP using suction casting technique. The structure, mechanical property and corrosion behaviors of the composite have been evaluated by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), mechanical testing, electrochemical and immersion test. It is shown that the molten Mg-5Sn alloy has infiltrated not only into the pores but also into the struts of the HA+ß-TCP scaffold to forming a compact composite. The microstructure observation also shows that the Mg alloy contacts to the HA+ß-TCP closely, and no reaction layer can be found between Mg-5Sn alloy and scaffold. The ultimate compressive strength of the composite is as high as 176MPa, which is about four fifths of the strength of the Mg-5Sn bulk alloy. The electrochemical and immersion tests indicate that the corrosion resistance of the composite is better than that of the Mg-5Sn bulk alloy. The corrosion products on the composite surface are mainly Mg(OH)2, Ca3(PO4)2 and HA. Appropriate mechanical and corrosion properties of the (HA+ß-TCP)/Mg-5Sn composite indicate its possibility for new bone tissue implant materials.

Comparison of cytotoxicity of the (-)- and (+)-enantiomer of 2',3'-dideoxy-3'-thiacytidine in normal human bone marrow progenitor cells.

The effects of racemic cis-2',3'-dideoxy-3'-thiacytidine [(+/-)-BCH-189] and its two enantiomers on human myeloid and erythroid colony-forming cells were studied by clonogenic assays. The (+)-isomer was the most toxic with a median inhibitory concentration approximating 2 microM in both cell lineages. In contrast, concentrations of the (-)-isomer required for 50% inhibition of granulocyte macrophage colony-forming units (CFU-GM) and erythroid burst-forming units (BFU-E) were 33.9 +/- 15.1 and 169.4 +/- 87.9 microM, respectively. The racemic BCH-189 was quite toxic to these cells, but to a lesser extent than observed with 3'-azido-3'-deoxythymidine and 3'-fluoro-3'-deoxythymidine (positive controls).

Catabolic disposition of 3'-azido-2',3'-dideoxyuridine in hepatocytes with evidence of azido reduction being a general catabolic pathway of 3'-azido-2',3'-dideoxynucleosides.

3'-Azido-2',3'-dideoxyuridine (AzddU, CS-87) is a potent inhibitor of human immunodeficiency virus replication in vitro with low bone marrow toxicity. Although AzddU is currently being evaluated in clinical trials, its catabolic disposition is unknown. Pharmacokinetic studies in rhesus monkeys have demonstrated that a 5'-O-glucuronide is excreted in urine. The present study examined the catabolic disposition of AzddU is isolated rat hepatocytes, a model for the study at the cellular level of biosynthetic, catabolic and transport phenomena in the liver. Following exposure of cells to 10 microM [3H]AzddU, low intracellular levels of two catabolites, identified as 3'-azido-2',3'-dideoxy-5'-beta-D-glucopyranosyluridine (GAzddU) and 3'-amino-2',3'-dideoxyuridine (AMddU), were detected. Studies using rat microsomes demonstrated that GAzddU formation was only detected in the presence of uridine 5'-diphosphoglucuronic acid, and that the rate of AMddU formation increased significantly in the presence of NADPH. Under similar conditions, reduction of the 3'-azido function was also demonstrated herein with 3'-azido-2',3'-dideoxycytidine (AzddC), 3'-azido-2',3'-dideoxy-5-methylcytidine (AzddMeC) and 3'-azido-2',3'-dideoxyguanine (AzddG), suggesting that enzymatic reduction to a 3'-amino derivative is a general catabolic pathway of 3'-azido-2',3'-dideoxynucleosides at the hepatic site.

Selective protection of toxicity of 2',3'-dideoxypyrimidine nucleoside analogs by beta-D-uridine in human granulocyte-macrophage progenitor cells.

beta-D-Uridine protected human granulocyte-macrophage lineage cells in both semi-solid (granulocyte-macrophage colony-forming units, CFU-GM) and liquid cultures against the toxic effects of 3'-azido-3'-deoxythymidine (AZT), 3'-fluoro-3'-deoxythymidine (FLT) and a combination of AZT and FLT, without impairment of the activities of these respective drugs against human immunodeficiency virus (HIV) replication. In addition, beta-D-uridine also protected human CFU-GM against toxicity of the in vivo AZT metabolite, 3'-amino-3'-deoxythymidine (AMT). Beta-L-uridine and alpha-D-uridine, two stereoisomers of the natural form, and the base uracil, were unable to protect cells against either AZT or FLT toxicity, whereas beta-D-uridine-5'-bis(SATE)phosphotriester, a prodrug of beta-D-uridine-5'-monophosphate, successfully protected cells against AZT toxic effects, suggesting that beta-D-uridine needs to be metabolized to its nucleotides to exert a pharmacological effect. These data suggest in addition that AZT, FLT and AMT share a common target site(s) of toxicity involved in myelosuppression.

A new macromolecular antitumor antibiotic, C-1027. II. Isolation and physico-chemical properties.

A new macromolecular antibiotic C-1027 was obtained from the broth filtrate of Streptomyces globisporus C-1027 by precipitation with ammonium sulfate, DEAE-cellulose column chromatography and gel filtration chromatography on a Sephadex G-75 column. This antibiotic, prepared as a white powder, is an acidic polypeptide having an isoelectric point of pH 3.5-3.7 and a molecular weight of 15,000 as determined by SDS-polyacrylamide gel electrophoresis and gel filtration chromatography. The acid hydrolysate of the purified antibiotic C-1027 contained no methionine or tryptophan. From the physico-chemical data, it may be considered to possess a very labile non-protein chromophore.

A new macromolecular antitumor antibiotic, C-1027. I. Discovery, taxonomy of producing organism, fermentation and biological activity.

Strain C-1027, an actinomycete isolated from a soil sample collected in China, was found to produce the new antibiotic, C-1027. From taxonomical studies on its morphological, cultural and physiological characteristics, this antibiotic-producing strain was identified as Streptomyces globisporus C-1027. Antibiotic C-1027 has antimicrobial activity against most Gram-positive bacteria but not against Mycobacterium sp. or Gram-negative bacteria. This antibiotic shows remarkable activity in spermatogonial assay and potent cytotoxicity against KB carcinoma cells in vitro, and exhibits inhibition on transplantable tumors in mice.

New antibiotics 4181-A and B from Streptomyces griseus; taxonomy, fermentation, isolation and characterization.

The new antibiotics 4181-A and B were isolated from the fermentation broth of Streptomyces griseus, a soil isolate. Their molecular formulae were determined as C29H21NO9 and C28H19NO9, respectively. The UV, IR and NMR spectra suggest that they possess a quinone moiety in their structures. They were found to have antibacterial, antifungal and antitumor activity.