Immunization with Live-Attenuated RHΔhad2a Strain Confers Partial Protective Immunity against Acute and Chronic Infection of Toxoplasma gondii in Mice.

Toxoplasmosis caused by Toxoplasma gondii is an important zoonosis of human and animal health significance. Current chemical therapeutics have side effects, and no commercially available vaccine is licensed for the prevention of toxoplasmosis in humans and most animals. Developing a safe and effective vaccine with long-term protection against T. gondii infection is necessary to control toxoplasmosis. HAD2a is a key member of the haloacid dehalogenase (HAD) phosphatase family, which is essential for T. gondii daughter budding. However, the role of HAD2a in T. gondii virulence remains unknown. In this study, we successfully constructed the had2a gene knockout strain in the T. gondii-type I RH strain (RHΔhad2a) and determined its role in virulence and vaccination. These results demonstrate that HAD2a played an important role in parasite daughter budding and in vitro replication. Knockout of the had2a gene attenuated the virulence of the T. gondii-type I RH strain. Vaccination with RHΔhad2a tachyzoites induced a Th1-biased immune response, provided partial protection against acute T. gondii infection in mice by highly virulent tachyzoites of RH and PYS (ToxoDB#9, Chinese I) strains, and conferred strong protection against challenge infection by cysts and oocysts of the less virulent type II Pru strain. These results demonstrate that T. gondii had2a is important for its in vitro proliferation and virulence in mice and that RHΔhad2a may be used as a candidate strain to generate a multiple gene knockout live-attenuated strain or be collaboratively applied with other live-attenuated strains to confer more effective protection against T. gondii infection.

Seroprevalence and Risk Factors of Chlamydia Infection in Cattle in Shanxi Province, North China.

The information on Chlamydia infection in cattle is limited in Shanxi Province, north China. This study aimed to investigate the seroprevalence and risk factors of Chlamydia and Chlamydia abortus infection in cattle in Shanxi Province. In November 2020, a large-scale investigation of Chlamydia seroprevalence was conducted on 981 cattle serum samples collected from 40 cattle farms in 11 cities of Shanxi Province. The seroprevalence of Chlamydia and C. abortus was examined by indirect hemagglutination assay (IHA) and enzyme-linked immunosorbent assay (ELISA), respectively. The seroprevalence of Chlamydia and C. abortus was 52.29% (513/981) and 2.96% (29/981), respectively, in cattle in Shanxi Province. Location was identified as a risk factor for Chlamydia and C. abortus infection (p < 0.05). Under different management patterns, the seroprevalence of Chlamydia and C. abortus in large-scale animal farming companies was higher than that in household animal farms and animal farming cooperatives, and only the seroprevalence of Chlamydia was significantly different in different management patterns (p < 0.01). The results showed that there was higher seroprevalence of Chlamydia in cattle in Shanxi Province, while C. abortus was not the dominant species. This study provided baseline information on Chlamydia infection in cattle in Shanxi Province, which constitutes valuable data for monitoring livestock health and preventing potential zoonoses.

The Seroprevalence of Chlamydia Infection in Sheep in Shanxi Province, China.

Chlamydia, an obligate intracellular bacterium, can cause chlamydiosis in humans and animals worldwide and also leads to serious economic losses to the sheep industry. However, the information on Chlamydia infection in sheep was limited in Shanxi Province, northern China. In the present study, a total of 984 serum samples of sheep were collected from 11 regions in Shanxi Province, northern China in the autumn of 2020. The antibodies against Chlamydia and Chlamydia abortus were examined by the indirect hemagglutination assay (IHA) and indirect enzyme-linked immunosorbent assay (ELISA), respectively. The result showed that 351 (35.67%, 95% CI 32.68-38.66) of 984 serum samples were positive for Chlamydia, and the seroprevalence ranged from 6.67% to 70.79% among the different regions. In addition, antibodies to C. abortus infection were detected in 78 (7.93%, 95% CI 6.24-9.61) of 984 serum samples, and the seroprevalence ranged from 6.24% to 14.81% among the different regions. This is the first report on the seroprevalence of Chlamydia and C. abortus in sheep in Shanxi province, northern China. The findings provide baseline information for preventing and controlling Chlamydia infection in sheep in Shanxi Province, China.

[Treatment of senile lumbar spinal stenosis by unilateral approach and bilateral decompression with large channel endoscopy].

OBJECTIVE: To evaluate clinical effect of unilateral approach and bilateral decompression via large channel endoscopic system for the treatment of lumbar spinal stenosis. METHODS: The clinical data of 32 patients with lumbar spinal tenosis treated by unilateral approach and bilateral decompression via large channel endoscopy from February 2018 to February 2019 were retrospectively analyzed. There were 18 males and 14 females, aged 65 to 84 years old with an average of (70.6± 8.4) years. The course of disease was from 1 to 12 years. All 32 cases were accompanied by numbness or pain in the lower limbs, of which 28 cases were accompanied by intermittent claudication. Narrow segments were L3, 4 of 2 cases, L4, 5 of 19 cases, L5S1 of 13 cases, including double segments of 2 cases. Preoperative imaging showed 3 cases of central canal stenosis, 21 cases of bilateral lateral recess stenosis and 8 cases of mixed stenosis. Operation time and complications were recorded. X-ray, CT and MRI were analyzed at 3 days, 3 months and 1 year after operation. Visual analogue scale(VAS), Oswestry Disability Index (ODI), single continuous walking distance(SCWD) were observed before and after operation. Modified Macnab standard were used to evaluate the clinical effect at 1 year after operation. RESULTS: All the patients were followed up for 12-24 (17.68±2.43) months and all operations were successfully completed with the operation time of 70-160(85.64±11.94) min. Spinal dural tear occurred in 1 case during the operation, and sensory disturbance in the other side of lower limb in a short period of time occurred in 2 cases, all improved after corresponding treatment. Postoperative imaging showed that the spinal canal was significantly enlarged and the nerve root was fully released. Before operation and 3 days, 3 months, 1 year after operation, VAS scores of low back pain were 4.62 ±1.41, 2.73 ±1.35, 1.21 ±1.17, 1.11 ±0.34, respectively;VAS scores of leg pain were 6.83 ± 1.71, 3.10±1.50, 1.08±0.19, 0.89±0.24, respectively. VAS scores of low back pain and leg pain each time point after operation were obvious improved (P<0.05); there was significant difference between 3 months and 3 days after operation(P<0.05), and there was no significant difference between 3 months and 1 year after operation (P>0.05). Before operation and 3 days, 3 months, 1 year after operation, ODI scores were 38.40 ±6.48, 18.42 ±2.40, 5.48 ±0.77, 3.05 ±0.28, respectively; SCWD was (47.48±5.32) m, (52.89±11.23) m, (245.43±18.94) m, (468.97±55.87) m, respectively. The differences in ODI score and SCWD postoperative time points were statistically significant compared with those before operation (P<0.05). The difference between 3 months and 3 days after operation was statistically significant (P<0.05). The difference between 1 year and 3 months after operation was statistically significant (P<0.05). According to Macnab standard to evaluate clinical effect at 1 year after operation, 15 cases got excellent results, 14 good, 3 fair. CONCLUSION: It is a safe and effective way to treat lumbar spinal stenosis with unilateral approach and bilateral decompression via large channel endoscopic system. It has the advantages of sufficient decompression, less trauma, fast recovery, high safety and low incidence of postoperative complications. It can minimize the damage to the stable structure of the lumbar spine and is an ideal minimally invasive operation for the treatment of lumbar spinal stenosis.

Posterior percutaneous endoscopic versus traditional surgery for cervical disc herniation: A protocol for systematic review and meta analysis.

BACKGROUND: Posterior percutaneous endoscopic cervical diskectomy (P-PECD) can be used posterior microdiscectomy for cervical disc herniation. But only some small sample sizes of clinical studies have evaluated the efficacy and safety of P-PECD. This study aim to evaluated the efficacy and safety of P-PECD compared with traditional open surgery. METHODS: We will search the following seven electronic databases from their initiation to the May 1, 2020: PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), Chinese Biomedical Literature Database (CBM) and Wanfang database. All randomized controlled trials, non-randomized controlled trials and retrospective case controls that compared the efficacy and safety of P-PECD and traditional open surgery in the treatment of cervical disc herniation will be included. The pooled odds ratio with 95% credible intervals (CIs) was used for the dichotomous variables. The mean difference with 95% CIs was used for the continuous variables. All analyses were conducted by Comprehensive Meta Analysis 2.0. A 2-tailed P value < 0.05 is considered statistically significant. RESULTS: The results of systematic review and meta-analysis will be submitted to a peer-reviewed journal. CONCLUSION: Our study will provide clarity regarding for clinicians to choices best surgical approach for patients with cervical disc herniation. Any changes that need to be made during the process of this study will be explained in the final full-text publication. PROTOCOL REGISTRATION NUMBER: CRD42020164011.

Fingolimod (FTY720) improves postoperative cognitive dysfunction in mice subjected to D-galactose-induced aging.

Neurocognitive dysfunction is a common postoperative complication, especially in older adult patients. Fingolimod (FTY720) is a sphingosine-1-phosphate receptor modulator that has been found to be neuroprotective in several animal models of central nervous system disease. However, few reports have examined whether FTY720 could mitigate postoperative cognitive dysfunction. In this study, we investigated whether FTY720 could prevent postoperative neurocognitive impairment in mice subjected to D-galactose-induced aging. We induced an accelerated model of aging by administering an intraperitoneal injection of D-galactose. Subsequently, we performed a partial hepatolobectomy under sevoflurane anesthesia. FTY720 (1 mg/kg) was administered intraperitoneally 3 hours before and 24 hours after anesthesia and surgery. Our results indicated that anesthesia and surgery significantly impaired spatial memory in the Y-maze test 6 hours after surgery. We also found that problem solving ability and long-term memory in the puzzle box test on postoperative days 2-4 were significantly improved by FTY720 treatment. Immunohistochemical staining and western blot assay demonstrated that FTY720 significantly inhibited microglial activation in the hippocampal CA1 region of mice 6 hours and 3 days after anesthesia, and down-regulated the expression of synaptic-related proteins postsynaptic density protein 95 and GluR2 in the hippocampus. These results indicate that FTY720 improved postoperative neurocognitive dysfunction in mice subjected to D-galactose-induced aging. This study was approved by the Experimental Animal Ethics Committee of the Third Xiangya Hospital of Central South University of China (approval No. LLSC (LA) 2016-025) on September 27, 2016.

Effect of self-alkalization on nitrite accumulation in a high-rate denitrification system: Performance, microflora and enzymatic activities.

The self-alkalization of denitrifying automatic circulation (DAC) reactor resulted in a large increase of pH up to 9.20 and caused a tremendous accumulation of nitrite up to 451.1 ± 49.0 mgN L(-1) at nitrate loading rate (NLR) from 35 kgN m(-3) d(-1) to 55 kgN m(-3) d(-1). The nitrite accumulation was greatly relieved even at the same NLR once the pH was maintained at 7.6 ± 0.2 in the system. Enzymatic assays indicated that the long-term bacterial exposure to high pH significantly inhibited the activity of copper type nitrite reductase (NirK) rather than the cytochrome cd1 type nitrite reductase (NirS). The terminal restriction fragment length polymorphism (T-RFLP) analysis revealed that the dominant denitrifying bacteria shifted from the NirS-containing Thauear sp. 27 to the NirK-containing Hyphomicrobium nitrativorans strain NL23 during the self-alkalization. The significant nitrite accumulation in the high-rate denitrification system could be therefore, due to the inhibition of Cu-containing NirK by high pH from the self-alkalization. The results suggest that the NirK-containing H. nitrativorans strain NL23 could be an ideal functional bacterium for the conversion of nitrate to nitrite, i.e. denitritation, which could be combined with anaerobic ammonium oxidation (Anammox) to develop a new process for nitrogen removal from wastewater.

Sialic acid accelerates the electrophoretic velocity of injured dorsal root ganglion neurons.

Peripheral nerve injury has been shown to result in ectopic spontaneous discharges on soma and injured sites of sensory neurons, thereby inducing neuropathic pain. With the increase of membrane proteins on soma and injured site neurons, the negatively charged sialic acids bind to the external domains of membrane proteins, resulting in an increase of this charge. We therefore speculate that the electrophoretic velocity of injured neurons may be faster than non-injured neurons. The present study established rat models of neuropathic pain via chronic constriction injury. Results of the cell electrophoresis test revealed that the electrophoretic velocity of injured neuronal cells was faster than that of non-injured (control) cells. We then treated cells with divalent cations of Ca(2+) and organic compounds with positive charges, polylysine to counteract the negatively charged sialic acids, or neuraminidase to specifically remove sialic acids from the membrane surface of injured neurons. All three treatments significantly reduced the electrophoretic velocity of injured neuronal cells. These findings suggest that enhanced sialic acids on injured neurons may accelerate the electrophoretic velocity of injured neurons.

Stiff substrates enhance cultured neuronal network activity.

The mechanical property of extracellular matrix and cell-supporting substrates is known to modulate neuronal growth, differentiation, extension and branching. Here we show that substrate stiffness is an important microenvironmental cue, to which mouse hippocampal neurons respond and integrate into synapse formation and transmission in cultured neuronal network. Hippocampal neurons were cultured on polydimethylsiloxane substrates fabricated to have similar surface properties but a 10-fold difference in Young's modulus. Voltage-gated Ca(2+) channel currents determined by patch-clamp recording were greater in neurons on stiff substrates than on soft substrates. Ca(2+) oscillations in cultured neuronal network monitored using time-lapse single cell imaging increased in both amplitude and frequency among neurons on stiff substrates. Consistently, synaptic connectivity recorded by paired recording was enhanced between neurons on stiff substrates. Furthermore, spontaneous excitatory postsynaptic activity became greater and more frequent in neurons on stiff substrates. Evoked excitatory transmitter release and excitatory postsynaptic currents also were heightened at synapses between neurons on stiff substrates. Taken together, our results provide compelling evidence to show that substrate stiffness is an important biophysical factor modulating synapse connectivity and transmission in cultured hippocampal neuronal network. Such information is useful in designing instructive scaffolds or supporting substrates for neural tissue engineering.

Glycosylation-induced depolarization facilitates subthreshold membrane oscillation in injured primary sensory neurons.

Subthreshold membrane potential oscillations (SMPO) in the injured dorsal root ganglion (DRG) neurons are involved in the generation of spontaneous activity, which can directly evoke neuropathic pain. Nerve injury usually triggers the synthesis of large quantities of membrane protein in nerve injured DRG neurons. Membrane proteins are glycosylated by addition of sugars, especially negatively charged sialic acid residues, which may depolarize the resting membrane potential (Vm), open voltage-gated channels in injured neurons, and cause spontaneous activity. In the present study, we aimed to determine if increased negative charge on the cell surface, carried by the sialic acid residues, could contribute to the generation of SMPO in injured DRG neurons. Intracellular recording was performed in DRG neurons following chronic constrictive injury (CCI) of the sciatic nerve. Results indicated that both A- and C-type injured DRG neurons exhibited a higher incidence of SMPO and more depolarized Vm than those of the control neurons. Ca(2+), Mg(2+), Mn(2+), or poly-lysine, a positively charged organic compound, when topically applied to the DRG, not only reduced SMPO but also caused a rapid hyperpolarizing shift in Vm. Topical application of neuraminidase to selectively remove sialic acid residues on the extracellular membrane normalized the depolarized Vm and inhibited both spontaneous and evoked SMPO. However, application of Ca(2+), Mg(2+), Mn(2+) or neuraminidase had no effect on excitability and Vm in normal neurons. The results demonstrated that the increase in negatively charged sialic acid residues on the extracellular membrane of neuronal somata is a critical factor in the generation of SMPO and hyperexcitability in injured sensory neurons.

[Determination of Pb and Al in blood and hair of child using transverse heated graphite furnace atomic absorption spectroscopy].

Pb and Al in blood and hair of child were determined by transverse heated graphite furnace atomic absorption spectrometry with NH4H2PO4 and Mg(NO3)2 as a modifier, which enhanced the temperature of ashing, eliminated the matrix interference and memorial effect. The method is rapid, simple and accurate. The characteristic mass of the method was 2.3 x 10(-11) g and 2.2 x 10(-11) g for Pb and Al respectively. The relative standard deviation of Pb and Al was 3.0% and 11.4%, respectively, and the recovery was 96%-102%.