[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.

Association of arterial stiffness in non-hypertensive offspring with parental hypertension: the Hanzhong adolescent hypertension cohort study

OBJECTIVE

Arterial stiffness may be an early marker for vascular changes associated with hypertension in young adults. Individuals with a family history of hypertension are at high risk of developing hypertension. We investigated whether arterial stiffness measured, such as mean arterial pressure (MAP) and brachial to ankle pulse wave velocity (baPWV), were increased in normotensive offspring with a parental history of hypertension.

PATIENTS AND METHODS

We compared MAP and baPWV in a sample of 1953 non-hypertensive participants (974 men, mean age 42±3 years) recruited in the previous Hanzhong adolescent hypertension cohort study. Standardized questionnaires, physical examinations and laboratory tests were used to obtain information, with a particular focus on family hypertension history, anthropometric, hemodynamic, and biochemical factors.

RESULTS

A total of 1039, 759, 155 participants had 0, 1, and 2 parents with hypertension, respectively. Parental hypertension was associated with elevated offspring MAP (in multivariable-adjusted models, B=1.5 mm Hg, 95% CI 0.8-2.2 for 1 parent with hypertension; B=3.0 mm Hg, 95% CI 1.8-4.3, for 2 parents with hypertension; p<0.001 for each). A significant positive correlation was also observed between MAP and baPWV (r=0.543, p<0.001). BaPWV displayed a similar correlation with parental hypertension in age-adjusted, sex-adjusted and body mass index (BMI)-adjusted models (B=23.1 cm/s, 95% CI 8.0-38.1, for 1 parent with hypertension, p<0.01; B=53.0 cm/s, 95% CI 25.8-80.2, p<0.001 for 2 parents with hypertension), but associations were attenuated in multicovariate models after adjustment for MAP. In multivariable-adjusted models, logistic regression analysis showed that the risk of belonging to the upper quartile of MAP was significantly increased for offspring whose parents had hypertension (OR=1.5, 95% CI 1.2-1.9, for 1 parent with hypertension; OR=2.3, 95% CI 1.6-3.4, for 2 parents with hypertension; p<0.001 for each). Similarly, the odds ratios of belonging to the upper quartile of baPWV increased (OR=1.3, 95% CI 1.1-1.6, for 1 parent with hypertension, p<0.05; OR=2.1, 95% CI 1.5-3.0, for 2 parents with hypertension, p<0.001, in age-sex-BMI-adjusted models), and were then brought down in the fully adjusted models including MAP, but the increase remained significant for 2 parents with hypertension (OR=1.6, 95% CI 1.0-2.3, p<0.05).

CONCLUSIONS

These findings provide evidence that arterial stiffness is higher in young-to middle-aged normotensive subjects with a family history of hypertension, suggesting that increased arterial stiffness may occur in the early stages during the pathogenesis of hypertension.

Flow-through sampling for electrophoresis-based microfluidic chips using hydrodynamic pumping

This work presents a novel electrophoretic microchip design which is capable of directly coupling with flow-through analyzers for uninterrupted sampling. In this device, a 3 mm wide sampling channel (SC) was etched on quartz substrate to create the sample inlet and outlet and the 75 microm wide electrophoretic channels were also fabricated on the same substrate. Pressure was used to drive the sample flow through the external tube into the SC and the flow was then split into outlet and electrophoretic channels. A gating voltage was applied to the electrophoretic channel to control the sample loading for subsequent separations and inhibit the sample leakage. The minimum gating voltage required to inhibit the sample leakage depended on the solution buffer and increased with the hydrodynamic flow-rate. A fluorescent dye mixture containing Rhodamine B and Cy3 was introduced into the sample stream at either a continuous or discrete mode via an on-line injection valve and then separated and detected on the microchip using laser-induced fluorescence. For both modes, the relative standard deviation of migration time and peak intensity for consecutive injections was determined to be below 0.6 and 8%, respectively. Because the SC was kept floating, the external sampling equipment requires no electric connection. Therefore, such an electrophoresis-based microchip can be directly coupled with any pressure-driven flow analyzers without hardware modifications. To our best knowledge, this is something currently impossible for reported electrophoretic microchip designs.

[Influences of taurine and micronutrients on nitric oxide synthase expression and cGMP content in rat retina]

AIM

To investigate the influence of taurine and micronutrients on visual signal transmission.

METHODS

Wistar rats were divided into three groups, that is control group, experiment group 1 and experiment group 2, and fed for 3 weeks with normal diet, 5 times and 10 times doses of requirements of taurine, vitamin A, vitamin B, zinc and selenium, then each treatment group were divided into light group and dark adaptation group. After feeding another 3 days in different environments with normal diet, all animals were killed and cGMP level and NOS expression were analysed in retina and retinogeniculate.

RESULTS

The NOS expression and cGMP contents of photoreceptor cells, visual cortex and retinogeniculate were increased in dark adaptation group compared with light group. Nutritional intervention could enhance the NOS staining in dark environment, increased the cGMP contents whether light or dark condition.

CONCLUSION

The distribution, expression and content of NO and cGMP are quite different in various light adaptation status. Taurine and micronutrient intervention may modurate the visual signal transmission or vision function mediated by the changes of NO or cGMP.