Effects of the source of information and knowledge of dengue fever on the mosquito control behavior of residents of border areas of Yunnan, China.

BACKGROUND: Strengthening the mosquito control measures undertaken by residents of an area where dengue fever is present can significantly decrease the spread of this disease. The aim of this study was to explore the effects of the source of information and knowledge of dengue fever on the mosquito control behavior of residents of areas at high risk of this disease to determine effective ways of enhancing this behavior. METHODS: A survey was conducted via face-to-face interviews or questionnaires between March and May 2021 in three regions of the province of Yunnan, China. The survey included basic information about the respondents, the source(s) of their dengue fever information, the level of their dengue fever knowledge, and the measures they had implemented to control mosquitoes. Principal component analysis was used to extract the main components of the sources of information. Correlation analysis and structural equation analysis were used to explore the impact of the sources of information and residents' dengue fever knowledge on their mosquito control behavior. RESULTS: Publicity achieved through mass media, including official WeChat accounts, magazines/newspapers, poster leaflets, television/radio and the Internet, had a direct effect on dengue fever knowledge and mosquito control behavior, and indirectly affected mosquito control behavior through dengue fever knowledge. Organized publicity campaigns, including information provided by medical staff and through community publicity, had a direct effect on dengue fever knowledge and indirectly affected mosquito control behavior through dengue fever knowledge. The residents' level of dengue fever knowledge had a significant, positive, direct effect on their mosquito control behavior. CONCLUSIONS: Mosquito control is an important measure for the prevention and control of outbreaks of dengue fever. An effective source of information can improve the level of dengue fever knowledge among residents and thus enhance their mosquito control behavior.

First Report of Pantoea stewartii subsp. stewartii Causing Bacterial Leaf Wilt of Sugarcane in China.

The pathogen of Pantoea stewartii subsp. stewartii (Pss) that is the causal agent of Stewart's bacterial wilt of corn also infects numerous experimental hosts of graminaceous plants (Pepper et al., 1967; Wang et al., 2012). However, little is known about this pathogen naturally infecting sugarcane. In 2017, we observed some sugarcane cultivars showing leaf blade bleaching at the disease initiation stage, which further resulted in development of blight and necrotic lesions (Figure 1-A and -B) in Zhanjiang, Guangdong province of China. To diagnose this putative disease, five symptomatic leaf samples were collected from different sugarcane cultivars. The Pss was found to infect these samples using the nested PCR with Pss-specific outer primers PS1/PS4 and inner primers Ps2r/Ps3r that targeted at the 16S rRNA gene of this pathogen (Wang et al., 2009). The expected 262-bp fragments from positive samples were amplified, cloned, and sequenced (GenBank accession no. MW015795-MW015799). BLASTN analysis revealed that these isolates had more than 99.5% nucleotide identify (222 bp out of 262 bp) with each other and with Pss strains (ATCC 8199 and DC283) as well as P. stewartii subsp. indologenes strains (SR2-12 and LMG 2632) after sequences were trimmed at the 5'- and 3'-terminal of inner primer sequences. In addition, these leaf samples were surface-sterilized with 75% alcohol followed by macerated and chopped in sterile water. Upon plating on solid NA medium at 28 °C for 24-36 h, the bacterial colonies exhibited yellow color with circular, convex, smooth and translucent edges (Figure 1-C). Straight rods and non-encapsulated cells were detected under transmission electron microscopy (Figure 1-D). Moreover, an identical colony termed as PSCN1 was isolated from sugarcane cultivar YZ08-1095 and was further confirmed by the PCR with a universal primer pair 63F (5'-CAGGCCTAACACATGCAAGTC-3') and 1387R (5'-GGGCGGWGTGTACAAGGC-3') that targeted at bacterial 16S rRNA gene (Marchesi et al., 1998). A 1362-bp DNA fragment sequence was obtained from PSCN1 strain and deposited on GenBank library (accession no. MW015767). Sequence analysis showed that PSCN1 shared 99.9-100% nucleotide identity (1315 bp out of 1362 bp) with the two reference strains of Pss (ATCC 8199 and DC283) after sequences were trimmed at the 5'- and 3'-terminal of primer sequences. According to Koch's postulates, pathogenicity test was carried out on YZ08-1095 plants with 3-5 fully developed leaf inoculated with the suspended cells (108 cells/ml) of PSCN1 strain by cutting the one-third of leaves before spraying with a suspension. Control plants were mock-inoculated with serial liquid nutrition agar medium. Two independent experiments were performed for pathogenicity assay and more than 28 plants of YZ08-1095 were used in each treatment. Plants were cultured in a growth chamber at 28 °C and 60% humidity under a 16 h light/8 h dark photoperiod. Leaves inoculated by the PSCN1 initially showed bleached, blight and wilting symptoms on leaf edges at seven days post-inoculation (dpi) (Figure 1-E and -F), which were similar to those symptoms observed in the fields. Control plants remained asymptomatic (Figure 1-G). The average incidence of diseased plant was 51.9% at 21 dpi. The bacteria were subsequently re-isolated from diseased leaves, and yielded colonies were completely identical to the PSCN1. Taken together, our data provides the valuable information for diagnosis and controlling this disease in sugarcane.

Asymmetric membrane capsules for delivery of poorly water-soluble drugs by osmotic effects.

A non-disintegrating polymeric capsule system, in which asymmetric membrane offers an improved osmotic effect, was used to deliver poorly water-soluble drugs in a control manner. The capsule wall membrane was made by a phase inversion process, in which asymmetric membrane was formed on stainless-steel mold pins by dipping the mold pins into a coating solution containing a polymeric material followed by dipping into a quench solution. This study evaluates the influence of coating formulation that was cellulose acetate (CA), ethylcellulose (EC), and plasticizer (glycerin and triethyl citrate). Results show capsule that made by CA with glycerin (formulation A), which appear in asymmetric structure and are able to release chlorpheniramine maleate (CM) in significant percentage. Two poorly water-soluble drugs of felodipine (FL) and nifedipine (NF) were selected as the model drug to demonstrate how the controlled release characteristics can be manipulated by the design of polymeric capsules with an asymmetric membrane and core formulations. Results show that sodium lauryl sulfate (SLS) is able to promote the release of FL from polymeric capsules prepared with CA with asymmetrical membrane. The addition of solubilizer, including RH40, PVP K-17, and PEG 4000 could enhance the release of FL but with an extent not being related to its solubility. Based on these results, influence of core formulation variables, including the viscosity and added amount of hydroxypropyl methylcellulose (HPMC), the added amount of SLS, and drug loading were examined on the release of NF. It was found that HPMC of 50 cps was suitable to be a thickening agent and both added amount of HPMC and SLS showed a comparable and profoundly positive effect, whereas NF loading had no influence on the drug release percent and rate. There existed a synergistic interaction between HPMC and SLS on the release percent and rate.