[Detection of drug resistance genes of mycobacterium tuberculosis by rolling circle amplification technique with multicolor fluorescent probes].

The aim of this study was to construct a simple, rapid and ultra-sensitive optical biosensing technique based on rolling circle amplification (RCA), and to apply it to multiple detection of drug-resistant genes of mycobacterium tuberculosis. The common mutation sites of isoniazid, rifampicin and streptomycin resistance genes are katG315 (AGC➝ACC), rpoB531 (CAC➝TAC) and rpsL43 (AAG➝AGG). For these three gene sites, from February 2020 to May 2021, in the Department of Laboratory Medicine of the First Affiliated Hospital of Army Military Medical University, the padlock probe (PLP), primers and capture probes were designed. And a solid-phase RCA constant temperature amplification reaction system based on magnetic beads was constructed and the experimental parameters were optimized. The RCA products were accurately captured by the multicolor fluorescent probes (Cy3/Cy5/ROX), and the single-tube multiple detection of three mutation genes was realized. The sensitivity, specificity and linear range of this method were further verified. The results showed that the response range of katG315 in the same reaction system ranged from 1.0 pmol/L to 0.1 nmol/L. The response range of rpoB531 and rpsL43 ranged from 1.0 pmol/L to 50.0 pmol/L and 1.0 pmol/L to 20.0 pmol/L, and the method had good specificity and sensitivity, and could accurately identify single base mutations in mixed targets, with the minimum detection limit as low as 1.0 pmol/L. The recoveries of simulated serum samples were 95.0%-105.2%. In conclusion, the constant temperature amplification multiple detection method constructed in this study can quickly realize the single-tube multiple detection of three drug resistance mutation sites. This technology is low-cost, simple and rapid, and does not rely on large equipment, providing a new analysis method for pathogen drug resistance gene detection.

[Climbing-upward inhibition of Oncomelania hupensis by niclosamide combination].

OBJECTIVE: To develop a combination of molluscicide/insecticide with a good molluscicidal effect, especially an inhibitory effect on climbing-upward of Oncomelania hupensis. METHODS: Experiments on molluscicidal and snail-climbing inhibition effect of the combination of niclosamide and shachongding [(dimethylamine) trithacyclohexane hydrochloride] were conducted by immersion and spraying in laboratory. RESULTS: The combination of niclosamide (0.2 mg/L) and shachongding (0.1 mg/L) showed an inhibition of 92.67% of snails to climb up. There was no significant difference in molluscicidal effect between the combination (LC90 0.198 mg/L) and niclosamide alone (LC90 0.207 mg/L). CONCLUSION: The combination showed an effective inhibition on the climbing-upward of snails in water so as to improve the molluscicidal effect and reduce the cost of mollusciciding.

[Tentative study of geographical epidemiology of schistosomiasis japonica in Yunnan province].

Schistosomiasis prevails in 17 counties and cities in Yunnan Province. Approximately, a population of 301,511 were affected and the snail-ridden area amounted to 219,000,000m2 in the past years. These endemic areas were not evenly distributed, but rather scattered. The endemic foci were vertically distributed at an altitude of 1,350-2,450 metres above sea level. Human cases were found mostly in areas with an elevation of greater than or equal to 1,800 metres, and became progressively fewer with the ascent. However, in areas with an-elevation of less than or equal to 1800 metres, the infection rate in the inhabitants decreased with the descent. In areas with an average temperature of 11.8-19.5 degrees C and the annual rainfall up to 574-970mm, transmission of the schistosomiasis was always present, suggesting an annual mean temperature around 15.7 degrees C and rainfall 800-900mm were favourable factors for schistosomiasis transmission. The cultivated areas with paddy soils were most suitable for the breeding of Oncomelania snails, where schistosmiasis was severely prevalent. Only a few Oncomelania snails and patients were observed in areas covered with red loam. No patient or snail was found in areas with brown loam or mountain meadow soil.

[Studies on negative conversion of schistosome-infected snails in mountainous region of Yunnan].

The monthly cercaria shedding of 90 artificially infected Oncomelania snails was observed under a field condition in mountainous region, Shitoudi Village, Weishan County, Yunnan Province. The results showed that 20% of teh snails shed cercaria monthly, 42.2% could shed irregularly and 37.8% stopped releasing cercariae after several times of shedding. Final direction of the snails showed that none cercaria or sporocyst could be found in part of the snails. A total of 304 naturally infected snails were observed individually every month. Samples were taken each month from the snails which did not shed cercaria, then dissected and examined. The negative conversion rate was calculated in the second, third, fourth, fifth and sixth month after the first shedding, which were 36.1, 50.0, 41.0, 39.8 and 2.6% respectively.

Intra- and intermolecular C-h.pi interactions in bis[benzyl 3-(fluoren-9-ylidene)dithiocarbazato-N3,S]nickel(II).

The title compound, [Ni(C(21)H(15)N(2)S(2))(2)], has a novel cis configuration with two fluorene moieties on the same side. The Ni atom is in a square-planar configuration. The molecular packing is stabilized by intramolecular stacking between the fluorene moieties and extensive C-H.pi interactions.

Bis[2,2'-ethylenedioxydibenzaldehyde bis(thiocarbohydrazide)] tris(pyridine) solvate.

The title compound, a novel 30-membered 2:2 macrocyclic thiocarbohydrazone, C(34)H(32)N(8)O(4)S(2) x 3C(5)H(5)N, has been prepared and crystallographically characterized. The molecule of the compound is twisted. One dioxabutane group is boat-like in shape, whereas the other is highly disordered. The crystal structure is stabilized by inter- and intramolecular hydrogen bonds.