Hyaluronic acid is a linear acid mucopolysaccharide composed of repeating disaccharide glucuronic acid and N-acetyl-glucosamine units,which is widely used in medicine,cosmetics,food and other fields.Traditional studies have made significant achievements in improving the production of hyaluronic acid by optimizing the fermentation parameters,but have reached the upper limit,and the natural strains have the increasing disadvantages of high cost of fermentation medium and pathogenicity.With the rapid development of molecular biology technology and the continuous research on the genes related to hyaluronic acid synthesis,the research focus has gradually shifted to the use of genetic engineering technology to construct high yield,safe and specific molecular weight hyaluronan genetically engineered strains.Here the strategies and research progress of genetic engineering for the production of hyaluronic acid were reviewed.

Objective To investigate the expression of PD‐L1 in the CD4+CD25hiCD127low/‐ Treg cells in the peripheral blood of colon cancer and the correlation with clinical stage .Methods The expression of PD‐L1 on CD4+CD25hiCD127low/‐Treg cells from 47 samples of the peripheral blood of colon cancer was analyzed by flow cytometry .Results Compared with those from healthy do‐nor ,the proportion of CD4+CD25hiCD127low/‐Treg cells and expression of PD‐L1 on these cells increased significantly (P<0 .01) . Further analysis showed that expression of PD‐L1 increased with the increase of clinical stage of colon cancer (P<0 .01) ,and de‐creased significantly after postoperation (P<0 .05) .Conclusion Increase of proportion of CD4+CD25hiCD127low/‐Treg cells and the expression of PD‐L1 may enhance the suppression of antitumor immunity ,and thereby promote tumor immunoescape .

Molecularly imprinted polymers for dimethoate recognition were synthesized by the precipitation polymerization technique using methyl methacrylate (MMA) as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as the cross-linker. The morphology, adsorption and recognition properties were investigated by scanning electron microscopy (SEM), static adsorption test, and competitive adsorption test. To obtain the best selectivity and binding performance, the synthesis and adsorption conditions of MIPs were optimized through single factor experiments. Under the optimized conditions, the resultant polymers exhibited uniform size, satisfactory binding capacity and significant selectivity. Furthermore, the imprinted polymers were successfully applied as a specific solid-phase extractants combined with high performance liquid chromatography (HPLC) for determination of dimethoate residues in the cucumber samples. The average recoveries of three spiked samples ranged from 78.5% to 87.9% with the relative standard deviations (RSDs) less than 4.4% and the limit of detection (LOD) obtained for dimethoate as low as 2.3μg/mL.

Objective To explore the application of submental ultrasonongraphy (SUS) in the assessment of oropharyngeal swallowing disorders in children with cerebral palsy.Methods Seventeen children with cerebral palsy and oropharyngeal swallowing difficulties (7 on nasal feeding,10 on oral feeding) constituted the treatment group while 20 normal counterparts formed the control group.SUS was applied to measure any changes in the thickness of the tongue muscle and the range of hyoid bone displacement when they swallowed 5 ml of water.The results were compared with those assessed using the functional oral intake scale to decide the best cut-off point for detecting tube-feeding-dependent dysphagia.The intraclass correlation coefficient (ICC) of the 20 children in the control group was calculated to evaluate the intra-rater and inter-rater reliability of SUS.Results The average tongue muscle thickness change and hyoid bone displacement amplitude of the children on nasal feeding were significantly smaller than those of the children without nasal feeding and the normal children.The best cut-off point for the tongue muscle thickness change data was 1.0 cm,and that of the hyoid bone displacement amplitude was 1.5 cm.All of the ICCs were above 0.4,indicating good intra-rater and inter-rater reliability for the SUS examination.Conclusion Submental ultrasonongraphy can help assess the swallowing function of children with oropharyngeal swallowing disorders.

Objective To investigate the applicability of Bakes Caregiving Outcom Scale(BCOS) in the study of primary family caregivers'burden of stroke survivors. Methods The BCOS was used to inves-tigate the 180 primary family caregivers of stroke survivors.The applicability of BCOS was evaluated by in-ternal consistency,construct validity and criterion-related validity. Results The correlation coefficient be-tween the items and the total BCOS score was 0.408～0.725 (P ＜ 0.01 ).The total Cronbach's α was 0.877.Factor analysis used for examining the construct validity showed that 3 components were extracted and their accumulated contribution rate reached 60.93%.Factor loading of each item ranged from 0.510 to 0.875.The criterion-related validity was - 0.461 by using self-rated burden as a criterion(P ＜ 0.01 ). Conclusions BCOS is applicable in the evaluation of the primary family caregivers' burden of stroke survivors.

Objective:To observe the effect of combining transcranial direct current stimulation (tDCS) with functional electrical stimulation-assisted cycling (FES-cycling) on lower limb motor function early after a stroke.Methods:Thirty-seven survivors of a recent stroke were divided into a tDCS treatment group ( n=18) and a pseudo-stimulation group ( n=19). While receiving routine rehabilitation training and clinical drug treatment, the tDCS treatment group also cycled in response to functional electrical stimulation while simultaneously receiving tDCS anode stimulation of the motor cortex M1 area. The pseudo-stimulation group followed the same protocol but with the tDCS stimulation inactivated. Both groups were treated for 20min daily, 5 days weekly for 4 weeks. Before and after the 4 weeks of treatment, the lower limb motor function, walking ability and ability in the activities of daily living of both groups were evaluated using the Fugl-Meyer assessment scale for the lower extremities (FMA-LE), the timed up and go test (TUGT) and the modified Barthel index (MBI) respectively. Transcranial magnetic stimulation was used to detect each subject′s cerebral cortex motor threshold (CMT) , cortical latency (CL) and central motor conduction time (CMCT) as well as the amplitude (Amp) of the motor evoked potential of the lower limb primary motor cortex (M1 area). Results:After 4 weeks of treatment, the average FMA-LE and MBI scores and TUGT times of the two groups had improved significantly compared with those before treatment. The average FMA-LE score and TUGT time of the tDCS group were significantly better than those of the pseudo-stimulation group. The average CMT, CL and CMCT in both groups were significantly lower than those before the intervention, while the average Amp had increased significantly, but there were significant differences in the average CMT, Amp, CL and CMCT between the two groups after the 4 weeks of treatment.Conclusions:Transcranial direct current stimulation combined with cycling assisted by functional electrical stimulation can effectively stimulate excitability in the motor cortex soon after a stroke. That should promote the recovery of nerve activity and lower limb function.

Objective: To establish the mouse aorta dissection (AD) model through drinking water containing β-aminopropionitrile (BAPN). Methods: Forty 3-week-old C57B1/6J male mice were divided into four groups according to randomized block design: control, 0.2, 0.4 and 0.8 g·kg^-1·d^-1 BAPN groups (dissolving respective dose of BAPN in the drinking water, n=10 each group). Arterial systolic blood pressure and heart rate were measured weekly in conscious, restrained mice using a noninvasive computerized tail-cuff system. Mice those died of rupture of aortic dissecting aneurysm during the study were autopsied and the aorta was examined. After 4 weeks, survived mice were sacrificed by an overdose of sodium pentobarbital and the whole aorta was harvested and analyzed. Results: The incidence of AD and the mortality of ruptured AD was 0 and 0 in control group, 30% (3/10) and 20% (2/10) in 0.2 g·kg^-1·d^-1 BAPN group, 50% (5/10) and 40% (4/10) in 0.4 g·kg^-1·d^-1 BAPN group, 90% (9/10) and 70% (7/10) in 0.8 g·kg^-1·d^-1 BAPN group (both P<0.05 vs. control group). The incidence of AD and the mortality of ruptured AD increased in proportion to BAPN concentration increase. In 0.8 g·kg^-1·d^-1 BAPN group, 7 mice died of dissecting aneurysm rupture during the experiment, among which 5 dissecting aneurysms were mainly located in the thoracic aorta and 2 dissecting aneurysms in abdominal aorta. The diameters of thoracic aorta and abdominal aorta were (1.38±0.19) and (1.23±0.13) mm in control group, (2.43±1.56) and (1.30±0.26) mm in 0.2 g·kg^-1·d^-1 BAPN group, (2.45±1.28) and (1.30±0.31) mm in 0.4 g·kg^-1·d^-1 BAPN group, (2.87±0.57) and (1.95±0.81) mm in 0.8 g·kg^-1·d^-1 BAPN group (both P<0.05 vs. control group). The diameters of thoracic aorta and abdominal aorta in mice also increased in proportion with BAPN concentration increase. Furthermore, blood-filled false lumen formation and elastic fibers fragmentation were evidenced in hematoxylin-eosin stained and Vitoria blue-Sirius red stained aortic cross-sections of mice in the 0.8 g·kg^-1·d^-1 BAPN group. Conclusion BAPN treatment induced aortic dissection model in C57Bl/6J mice can serve as a useful wild-type mouse model for the mechanism and pharmaceutical studies of AD.

OBJECTIVE: To explore the clinical phenotype and pathogenic variants in a Chinese pedigree affected with Smith-Lemli-Opitz syndrome. METHODS: Peripheral blood samples were collected from five members, including two affected ones, from the pedigree for the extraction of genomic DNA. Whole exome sequencing was carried out, and candidate variants were verified by Sanger sequencing as well as reverse transcription sequencing at the RNA level. RESULTS: The proband and another affected child from the pedigree showed mental retardation, dyskinesia, microcephaly, micrognathia, anteverted nares, and 2/3 toe syndactyly. The proband also had hypospadia, single upper incisor, and lower serum cholesterol level. Both children were found to harbor a paternally derived c.278C>T (p.T93M) variant and a maternally derived c.907G>A (p.G303R) variant of the DHCR7 gene. Both were known pathogenic mutations. CONCLUSION The compound heterozygous mutations of c.278C>T (p.T93M) and c.907G>A (p.G303R) of the DHCR7 gene probably underlay the disease in this pedigree. Above finding has enabled early diagnosis and treatment of Smith-Lemli-Opitz syndrome.
Child ; Genetic Testing ; Humans ; Oxidoreductases Acting on CH-CH Group Donors/genetics* ; Pedigree ; Phenotype ; Smith-Lemli-Opitz Syndrome/genetics*

OBJECTIVE: To explore the genetic basis for a Chinese pedigree with suspected mitochondrial functional defects through combined next-generation sequencing (NGS), copy number variation sequencing (CNV-seq), and mitochondrial DNA (mtDNA) sequencing. METHODS: Clinical data of the proband and his family members were collected. The patient and his parents were subjected to family-trio whole-exome sequencing (WES), CNV-seq and mtDNA variant detection. Candidate variant was verified by Sanger sequencing. RESULTS: Trio-WES revealed that the proband has carried compound heterozygous variants of the NDUFS1 gene, including a paternally derived c.64C>T (p.R22X) nonsense variant and a maternally derived c.845A>G (p.N282S) missense variant. Both variants may cause loss of protein function. No variant that may cause the phenotype was identified by CNV-seq and mtDNA variant analysis. CONCLUSION Children with suspected mitochondrial disorders may have no specific syndromes or laboratory findings. A comprehensive strategy including mtDNA testing may facilitate the diagnosis and early clinical interventions.
Child ; China ; DNA Copy Number Variations ; Electron Transport ; Humans ; Mutation ; NADH Dehydrogenase/genetics* ; Pedigree

Objective:To investigate the association between serum zinc levels and convulsive brain injury in infants with mild gastroenteritis complicated with benign infantile seizures (BICE) and febrile seizures (FC).Methods:A case-control study method was conducted. 120 children with mild gastroenteritis and convulsion admitted to the First Affiliated Hospital of Hebei North University from January 2020 to January 2022 were enrolled as the research subjects. They were divided into BICE group and FC group according to the type of convulsion. The serum zinc level, the frequency and duration of convulsion, and the occurrence of convulsive brain injury in the two groups were recorded. Multivariate Logistic regression analysis was used to screen the risk factors for convulsive brain injury. The Spearman correlation method was used to analyze the association between serum zinc levels, clinical characteristics of convulsion and convulsive brain injury.Results:A total of 120 children were enrolled, of which 81 developed to BICE and 39 developed to FC during hospitalization. The serum zinc level of children in the FC group was significantly lower than that in the BICE group (μmol/L: 39.24±6.50 vs. 48.65±7.21, P < 0.01). In the BICE group and FC group, the serum zinc level in children with more than 2 convulsions was significantly lower than that in the children with one convulsion (μmol/L: 37.65±6.50 vs. 53.17±7.55 in the BICE group, and 30.27±5.58 vs. 44.16±7.57 in the FC group, both P < 0.01). Serum zinc level in children with convulsion duration ≥5 minutes was significantly lower than that in the children with convulsion duration < 5 minutes (μmol/L: 38.75±6.74 vs. 51.21±7.58 in the BICE group, and 31.08±5.46 vs. 45.19±7.25 in the FC group, both P < 0.01). Moreover, the serum zinc level of children with different convulsion frequency and duration in the FC group was significantly lower than that in the BICE group (all P < 0.01). Among the 120 children, 9 cases of convulsive brain injury occurred, and the incidence rate was 7.50%. The incidence of convulsive brain injury in the BICE group was 1.23% (1/81), which was significantly lower than 20.51% in the FC group (8/39, P < 0.01). The serum zinc level of children with convulsive brain injury was significantly lower than that of children with non-brain injury (μmol/L: 28.50±5.00 vs. 60.22±7.31, P < 0.01), and the number of convulsion was significantly higher than that of non-cerebral injury (≥ 2 convulsions: 100.00% vs. 1.80%, P < 0.01), and the duration of convulsion in children with brain injury was significantly longer than that of non-brain-injured children (convulsion duration ≥5 minutes: 100.00% vs. 11.71%, P < 0.01). Multivariate Logistic regression analysis showed that decreased serum zinc level [odds ratio ( OR) = 2.147, 95% confidence interval (95% CI) was 1.354-3.403], increased number of convulsion ( OR = 3.452, 95% CI was 1.266-9.417), and prolonged convulsion duration ( OR = 3.117, 95% CI was 1.326-7.327) were independent risk factor for convulsive brain injury in children with mild gastroenteritis and convulsion (all P < 0.05). Spearman correlation analysis showed that serum zinc level, convulsion ≥2 times, duration of convulsion ≥5 minutes and convulsion ≥2 times + convulsion duration ≥5 minutes were significantly negatively correlated with the occurrence of convulsive brain injury in FC children ( r values were -0.546, -0.517, -0.522, and -0.528, all P < 0.01). There was no significant correlation between serum zinc level, convulsion ≥2 times, convulsion duration ≥5 minutes and convulsion ≥2 times+convulsion duration ≥5 minutes and convulsive brain injury in BICE children ( r values were -0.281, -0.129, -0.201, -0.243, all P > 0.05). Conclusions:Serum zinc level is related to the characteristics of convulsive symptoms in children with mild gastroenteritis complicated with FC, and has a strong negative correlation with the occurrence of convulsive brain injury. Active targeted intervention and treatment may help reduce the incidence of brain injury in children.