[Surveillance of Oncomelania hupensis distribution and water levels in Gaoyou sections of the eastern route project of the South-to-North Water Diversion Project following operation of the project]

OBJECTIVE

To understand the distribution of Oncomelania hupensis snails and changes of water levels in Gaoyou sections of the Li Canal following the operation of the eastern route project of the South-to-North Water Diversion Project.

METHODS

The Oncomelania snails were monitored in the river banks and water bodies of Gaoyou sections of the Li Canal by means of systematic sampling combined with environmental sampling as well as collection of the floaters from 2014 to 2019, and the water levels were collected in Gaoyou sections of the Li Canal at the typical hydrological year before the operation of the eastern route project of the South-to-North Water Diversion Project and during the period between 2016 and 2019.

RESULTS

A total area of 235.42 hm² were investigated and a total of 75.8 kg floaters were collected in Gaoyou sections of the Li Canal from 2014 to 2019; however, no snails were found. The water level in Gaoyou sections of the Li Canal was predominantly high in the flood season and low in the dry season before the operation of the eastern route project of the South-to-North Water Diversion Project, and the water level was elevated in the dry season and relatively low in the flood season after the operation of the project.

CONCLUSIONS

Following the operation of the eastern route project of the South-to-North Water Diversion Project, the original river bank that is characterized by "land in winter and water in summer" has changed in Gaoyou sections of the Li Canal, which is not favorable for snail breeding.

[Survival time and influencing factors in multidrug-resistant tuberculosis patients in Wuhan, 2006-2014]

Objective: To investigate the survival time of multidrug-resistant tuberculosis (MDR-TB) patients and the influential factors in Wuhan. Methods: The relevant information were collected from TB management information system, cause of death reporting system and medical records by trained doctors. The univariate and multivariate Cox proportional hazards model were applied to analyze the factors affecting survival time of patients. Results: A total of 552 patients with MDR-TB were included in the analysis. After the diagnosis of MDR-TB, the cumulative survival rates from the first year to the third year were 0.94, 0.88, and 0.80, respectively. The mortality density of MDR-TB patients was 6.52/100 person-years, and the median survival time was (89.52±1.85) months. Kaplan-Meier analysis showed that the cumulative survival rate of the standardized treatment group was significantly higher than that of the non-standardized treatment group (Log rank=101.070, P<0.001). Compared with the patients aged <30 years, the HR of the patients aged 30-years and ≥60 years were 2.987 (95%CI: 1.268-7.036), 4.957 (95%CI: 1.942-12.653). Compared with the patients with the education level of high school and above, the HR of the patients with education level of junior high school/primary school and below were 1.908 (95%CI: 1.152-3.160), 1.681(95%CI: 1.033-2.735). Compared with the patients without diabetes, the HR of the patients with diabetes was 1.961(95%CI: 1.347-2.854). Compared with the patients without other serious diseases, the HR of the patients with other serious diseases was 2.597 (95%CI: 1.820-3.706). Compared with the patients who had been treated less than one time, the HR of the patients having previous treatment with more than 2 times was 1.611 (95%CI: 1.077-2.409). Compared with patients receiving standard MDR regimen treatment, the HR of the patients receiving no standard MDR regimen treatment was 3.155 (95%CI: 2.132-4.670). Conclusions: The cumulative survival rate of MDR-TB patients without standard treatment was significantly lower than that of patients with standard treatment. Older age, low educational level, diabetes mellitus, other serious diseases, more than two times treatment in the past, and receiving no multi-drug resistance regimen treatment were the risk factors affecting the survival of MDR-TB patients.

[Effectiveness of snail control by immersion of molluscicides through tide diversion in marshlands: a field evaluation]

OBJECTIVE

To compare the effectiveness of snail control between immersion of molluscicides through tide diversion and mollusciciding by spraying in marshland areas.

METHODS

Immersion of 26% suspension concentrate of metaldehyde and niclosamide through tide diversion and spraying 26% suspension concentrate of metaldehyde and niclosamide alone were employed for snail control in two neighboring snail-breeding marshlands, and snails were surveyed before and after mollusciciding. The mortality of snails and the density of living snails were estimated.

RESULTS

The density of living snails reduced by 72.19% and 100.00% 1 and 2 years after immersion of 26% suspension concentrate of metaldehyde and niclosamide through tide diversion, and 5.93% and 18.15% 1 and 2 years after spraying 26% suspension concentrate of metaldehyde and niclosamide alone.

CONCLUSIONS

Immersion of 26% suspension concentrate of metaldehyde and niclosamide through tide diversion is significantly superior to spraying 26% suspension concentrate of metaldehyde and niclosamide along for snail control, and implementation of immersion of 26% suspension concentrate of metaldehyde and niclosamide through tide diversion for more than 2 successive years may achieve a higher snail control efficiency.

Assay of serum arylesterase activity by fitting to the reaction curve with an integrated rate equation

BACKGROUND

Conventional enzyme activities make use of the initial reaction rate at high substrate concentrations. Because this is not always practical, alternative enzyme assays have been sought.

METHODS

Reaction curve fitting with an integrated rate equation was investigated to assay serum arylesterase (ArE) activity using phenyl acetate (PA) and p-nitrophenol acetate (PNPA) as substrates. At a much lower initial concentration of substrate (S(0)), the simplified integrated rate equation for the ArE reaction was ln(S(0)/S(i))=(V(m)/K(m)+K(d))t(i). Treating S(0) as a parameter, the enzyme activity as V(m)/K(m) was estimated through nonlinear least square fitting to reaction curve, and the multiplication of V(m)/K(m) by K(m) produced V(m). Spontaneous hydrolysis of the substrate with a rate constant, K(d), served as the background for the estimation of V(m)/K(m).

RESULTS

Substrate concentration at 8% of K(m) was well suited for the estimation of V(m)/K(m). With either substrate, the V(m)/K(m) showed a close relation to the percentage of substrate consumed, and was not affected by common systematic errors. With either substrate, the between-run precision for V(m)/K(m) was 6% (n>7), V(m)/K(m) was proportional to the amount of ArE and closely correlated with its initial rate. The upper limit of linearity by this integrated method was much higher than the initial rate method, while the detection limit was comparable. By using either V(m)/K(m) or the initial rate, there was negligible interference with ArE activity assay from triglycerides, bilirubin, and hemoglobin.

CONCLUSIONS

These results indicate the feasibility of the integrated method for routine assay of serum enzyme activity.