Early changes within the lymphocyte population are associated with the long term prognosis in severely injured patients / 北京大学学报(医学版)

OBJECTIVE@#To investigate the relationship between early lymphocyte responses and the prognosis in severely injured patients.@*METHODS@#Consecutive patients with severe trauma who were treated in Peking University People's Hospital Trauma Medical Center between June 2017 and June 2020 were enrolled in this restropective chart-review study. According to the responses of lymphocyte after severe injury, the patients were divided into three groups, group 1: lymphopenia-returned to normal; group 2: persistent lymphopenia; group 3: never lymphopenic, and the outcome of 28 d were recorded. Clinical data such as gender, age, base excess, mechanism of injury, Glasgow coma scale (GCS), injury severity score (ISS) and massive blood transfusion were collected. Perform statistical analysis on the collected clinical data to understand the trend of lymphocyte changes in early trauma and the relationship with prognosis. In order to eliminate the interference of age, stratification was carried out according to whether the age was ≥ 65 years old, in different age groups, they were grouped according to whether the length of stay was ≥ 28 d, and the relationship between lymphocyte trend and length of stay was discussed.@*RESULTS@#A total of 83 patients were included, 66 males and 17 females. The main injury mechanisms were traffic accident injuries and high-altitude fall injuries. The average ISS was (30±11) points. 65 patients had lymphopenia on the day of injury, 32 of them returned to normal on the 5th day, and the rest did not recover; the other 18 patients had normal lymphocyte levels after injury. Patients which are failure to normalize lymphopenia within the first 5 days following admission was related with the long hospitalization time and higher 28 d mortality rate. After further stratification by age, failure to normalize lymphopenia within the first 5 days following admission in the elderly group (age ≥65 years) was a risk factor for prolonged hospital stay (≥28 d), P=0.04. While in younger group, a high level of neutrophils within the first 5 d following admission was a risk factor for bad outcome.@*CONCLUSION@#A failure to normalize lymphopenia in severely injured patients is associated with significantly higher mortality and longer hospital stay. This study reveals lymphocytes can be used as a reliable indicator for the prognostic evaluation.

Risk factors for mechanical ventilation in patients with severe multiple trauma / 北京大学学报(医学版)

OBJECTIVE@#To eludicate the risk factors of mechanical ventilation and prolonged mechanical ventilation in patients with severe multiple injuries.@*METHODS@#Consecutive patients with severe multiple injures who were treated in Peking University People's Hospital Trauma Medical Center between December 2016 and December 2019 were enrolled in this restropective chart-review study. According to mechanical ventilation and ventilatory time, the patients were divided into mechanical ventilation (MV) group and non-mechanical ventilation (NMV) groups, prolonged mechanical ventilation (PMV) group and shortened mechanical ventilation (SMV) groups. Clinical data such as gender, age, base excess, mechanism of injury, Glasgow Coma Scale (GCS), abbreviated injury scale (AIS) and injury severity score (ISS) were collected. To indentify the risk factors of mechanical ventilation and prolonged mecha-nical ventilation, univariate and multivariate Logistic analyses were carried out.@*RESULTS@#In the present study, 112 patients (82 male, 30 female) with severe multiple injuries having a median age of 52 (range: 16-89 years) and a median ISS of 34 (range: 16-66) were enrolled. The primary mechanism of injury was traffic accident injury and falling injury. In the study, 62 and 50 patients were assigned to MV and NMV groups, respectively. Logistic analysis showed that GCS (OR=0.72, 95%CI: 0.53-0.92, P=0.03), base excess (OR=0.56, 95%CI: 0.37-0.88, P=0.002) and multiple rib fracture (OR=1.72, 95%CI: 1.60-2.80, P=0.012) were independent significant risk factors for mechanical ventilation after severe multiple injuries. Within the mechanical ventilation group, 38 and 24 patients were assigned to PMV and SMVgroups, respectively. Compared with the SMV group, the PMV group had a higher ISS and higher rate of severe head trauma. The length of hospital stay of PMV group was longer than that of SMV groups. Meanwhile, the incidence of tracheotomy in PMV group was high.@*CONCLUSIONS@#GCS, base excess and rib fracture might be independent risk factors for mechanical ventilation. Higher ISS and lower GCS might prolong the ventilatory time and the length of hospital stay. Meanwhile, the incidence of tracheotomy was high in PMV group because of the longer ventilatory time and poor consciousness.

Internal exposure levels of polycyclic aromatic hydrocarbons in children and adolescents: a systematic review and meta-analysis

Polycyclic aromatic hydrocarbons (PAHs) are widely found in the environment, and comparing to adults, children are more vulnerable to PAHs exposure. Urinary metabolites of PAHs are used as preferred biomarkers to estimate the PAHs exposure. Systematic review on the internal exposure level of children and adolescents is rare. We aimed to calculate the internal exposure levels of PAHs in children and adolescents and compare the levels of PAHs internal exposure in various children groups. We searched PubMed, OVID, Web of Science, EBSCO, ACS, and four Chinese databases, and all studies examining the urinary concentrations of PAHs in children and adolescent were identified. The total exposure level of 11 PAHs metabolites were pooled. Standard mean difference (SMD) and 95% confidence intervals (CIs) of PAHs urinary concentration were calculated and pooled by RevMan5.3 to compare the exposure levels of different children groups. We found that 1-OHPyr, 2-OHNap, 2-OHFlu, 3-OHPhe, and 4-OHPhe were five PAHs metabolites most commonly studied in existing studies in children, and their total exposure levels were 0.38 ± 0.98, 2.32 ± 4.83, 0.81 ± 1.54, 0.09 ± 0.14, 0.03 ± 0.10 μmol/mol creatinine, respectively. The meta-analysis showed that the levels of 1-OHPyr were higher in higher environmental exposure group (SMD = 0.21, 95% CI = 0.03~0.40), ETS exposure group (SMD = 0.31, 95% CI = 0.08~0.54), and 6~11 years group (SMD = 0.16, 95% CI = 0.09~0.24); the level of 2-OHNap (SMD = 0.27, 95% CI = 0.01~0.53) was higher in higher environmental exposure group; however, the levels of 3-OHPhe (SMD = - 0.34, 95% CI = - 0.57~- 0.12) and 4-OHPhe (SMD = - 0.48, 95% CI = - 0.69~- 0.28) were higher in lower environmental exposure group. The levels of 1-OHPyr (SMD = - 0.01, 95% CI = - 0.11~0.10) and 2-OHNap (SMD = 0.01, 95% CI = - 0.20~0.22) were not statistically different between boys and girls. In conclusions, we found that the internal diversity of PAHs existed in children and adolescents, and the level of 1-OHPyr in children and adolescents was in higher status compared with non-occupational people who do not smoke.

Expression and significance of tight junction proteins in the kidney in a mouse model of renal ischemia-reperfusion injury / 中国当代儿科杂志

OBJECTIVE@#To study the expression and significance of tight junction proteins (claudin-2, claudin-10, and claudin-17) in a mouse model of renal ischemia-reperfusion injury.@*METHODS@#A total of 152 male C57BL/6 mice were randomly assigned to control group (n=8), sham-operation group (n=72), and model group (n=72). The renal pedicles at both sides were clamped for 30 minutes to establish a mouse model of renal ischemia-reperfusion injury. According to the time points of reperfusion (0, 3, 6, 12, 24, 48, and 72 hours and 5 and 7 days), the sham-operation group and the model group were further divided into 9 subgroups, with 8 mice in each subgroup. RT-PCR and immunohistochemistry were used to measure the mRNA and protein expression of claudin-2, claudin-10, and claudin-17 in renal tissue.@*RESULTS@#The control and sham-operation groups had no significant changes in the mRNA and protein expression of claudin-2, claudin-10, and claudin-17 in renal tissue over the time of reperfusion (P>0.05). Compared with the control and sham-operation groups, the model group had decreased mRNA and protein expression of claudin-2 and claudin-10 after reperfusion, and the expression decreased gradually over the time of reperfusion, with the lowest levels at 24 hours of reperfusion (P<0.05). Compared with the control and sham-operation groups, the model group had increased mRNA and protein expression of claudin-17 after reperfusion, and the expression increased gradually over the time of reperfusion, with the highest mRNA level at 12 hours and the highest protein level at 24 hours of reperfusion (P<0.05).@*CONCLUSIONS@#Renal ischemia-reperfusion injury is closely associated with abnormal expression of tight junction proteins claudin-2, claudin-10, and claudin-17.

Association of prenatal and childhood environment smoking exposure with puberty timing: a systematic review and meta-analysis

OBJECTIVES@#Mothers who smoke during pregnancy or while their children are small were common in some populations. Epidemiological studies have tried to detect the effect of prenatal tobacco smoke (PTS), and childhood environmental tobacco smoke (ETS) on puberty timing have not shown a consensus results. We aimed to examine current evidence and estimate the associations between PTS or/and ETS and puberty timing.@*METHODS@#Seven databases were searched from inception to May 2017. All the cohort studies examining the associations between PTS and/or ETS and puberty timing were identified. Two reviewers independently screened all studies, evaluated the quality of eligible studies, and extracted the data. The quality assessment of the eligible cohort studies was based on the Newcastle-Ottawa Scale. Risk ratio (RR), standard mean difference (SMD), and 95% confidence intervals (CIs) were calculated and pooled by CMA (Version 2.0, Biostat, Inc., USA).@*RESULTS@#Compared with controls, girls with PTS and ETS exposure have an earlier age at menarche (SMD - 0.087, 95% CI 0.174 to - 0.000), and similar results were found in both PTS subgroup (SMD - 0.097, 95% CI - 0.192 to - 0.002) and prospective cohort subgroup (SMD - 0.171, 95% CI - 0.253 to - 0.090). And number of boys with early voice break in PTS group was significantly increasing than non-exposed boys (RR 1.34, 95% CI 1.29 to 1.40).@*CONCLUSIONS@#PTS exposure possibly decrease age of menarche of girls, and studies on boys were urgent needed. Appropriate and comprehensive outcome measures using unified criteria to classify puberty should be reported in future studies.

Study on Syndrome Development Rules before and after Treating Primary Nephrotic Syndrome with Hormone / 浙江中医药大学学报

Objective]Based on 346 cases of PNS patients using glucocorticoids observed during treatment, the main symptoms, syndrome differentiation of syndrome type of traditional Chinese medicine(TCM) by induction, and discusses its the evolution regularity of TCM Syndromes.[Methods]Develop a unified observation table, then clinicians recorded symptoms, signs, tongue picture and type of pulse to log on to observe truthfully and un-mistakbly table, after the end of observation, comprehensive analysis by the four examination methods, using a unified standards for TCM syndrome type determination. Discussion after glucocorticoids treatment of patients with PNS TCM syndrome objective laws of evolution.[Result]First ,TCM syndrome evolution:the results show that:before hormone treatment, Qi deficiency of spleen and kidney and Yang deficiency of spleen and kidney have become the most important type of syndrome;hormone use initial stages 1~4 weeks, Qi deficiency of spleen and kidney, deficiency of Qi and Yin, when the hormone used for 5~8 weeks. Yin deficiency of liver and kidney and deficiency of Qi and Yin occupied the main position; during the hormone withdrawal stage, the deficiency of Qi and Yin increased significantly; in the hormone maintain stage it was mostly deficiency of Yin and Yang and Yang deficiency of spleen and kidney. As for demonstration, in hormone therapy before a lot of patients suffering from retention of water and turbid damp;After the treatment of 1~4 weeks it was mostly humid heat ,turbid damp and blood stasis;the accompanying symptoms were mostly humid heat, blood stasis and pathogenic factor of wind after the treatment of 5-8 weeks ;Miscellaneous accompanying symptoms were very conspicuous except retention of water in the treatment of hormone withdrawal stage; In the hormone maintaining stage, the highest proportion of blood stasis compared with others. The use of hormone therapy, humid heat and blood stasis were more prominent than others. Second, after the hormone treatment(1~8weeks) the relationship between efficacy and TCM syndromes: A total of 130 patients enrolled, the 96 patients with Yin deficiency syndrome, the rest of the patients had no deficiency of Yin syndrome. The results indicated that Yin deficiency syndrome group serum albumin and 24-hour urinary protein excretion efficacy than those without Yin deficiency syndrome group, with statistical significance.[Conclusion] Glucocorticoids should belong to pure Yang medicine in traditional Chinese medicine, the body under the action of pure Yang drugs are prone to Yin deficiency symptoms, suggests that the higher the sensitivity to drugs, the clinical remission rate is also higher. This can be applied in clinical glucocorticoids and observe the change of the patients with syndrome, early in the patients' sensitivity to the glucocorticoids.

Expression and significance of microRNA-21 in acute kidney injury renal of mice / 中华实用儿科临床杂志

Objective To investigate the expression and significance of microRNA - 21(miR - 21)in acute kidney injury mice model at the different time points following ischemic/ reperfusion. Methods C57BL/ 6J mice were divided into 3 major groups:the control group(C group),sham operation group(S group)and ischemia - reperfusion group(IR group). Later 2 groups were divided into 9 sub - groups respectively according to the time following reperfu-sion. Automatic biochemical analyzer detected serum creatinine(Scr),blood urea nitrogen(BUN)level. HE staining detected renal pathological damage. Renal tubulointerstitial pathological score accessed pathological damage. Real time - PCR tested the expression of miR - 21 and mitogen - activated protein kinase kinase 3(MKK3)mRNA in renal respectively. Immunohistochemistry staining tested expression of MKK3. Results IR group's Scr,BUN levels gradually increased following reperfusion,24 h reached its peak,then gradually declined. The Scr,BUN level had statistically sig-nificant difference between IR group and S group at the same time subgroup from 3 h to 168 h following reperfusion(all P ﹤ 0. 01). The change of kidney damage and pathological changes of interstitial and tubular injury score consensus with renal function. miR - 21 increased gradually in renal ischemia after reperfusion,24 h peaked and then stabilized at this high level. miR - 21 was positively correlated with pathological tubulointerstitial injury from 0 h to 168 h after reperfu-sion(r = 0. 969,P ﹤ 0. 05). IR group's MKK3 mRNA and protein expression rose sharply following ischemia/ reperfu-sion,24 h peaked,and then gradually decreased. From 3 h to 168 h,the expression of MKK3 mRNA and proteins had significant difference at each same time points subgroups between IR group and S group(all P ﹤ 0. 01). Conclusions miR - 21 increases gradually in renal ischemia after reperfusion,24 h peaked and then stabilized at this high level. miR - 21 is positively correlated with pathological tubulointerstitial injury,which may be associated with the negative regulated relationship between miR - 21 and MKK3.

Protective mechanism of ischemic preconditioning on apoptosis induced by kidney ischemia - reperfusion / 中华实用儿科临床杂志

Objective To investigate the protective effect of ischemia preconditioning(IPC)on apoptosis in-duced by renal ischemia - reperfusion(IR)and relations to the changing expressions of Bcl - 2,Bax in rat kidney. Methods Ischemia models were induced by clipping bilateral renal pedicles for 30 min by using the artery clamp;IPC group was induced by clipping bilateral renal pedicles for 15 min,4 days later IR was performed again by clipping bila-teral renal pedicle for 30 min. Rats were randomly divided into 5 groups with 5 animals in each group:control group(C group),sham - operation group(S group),IR group,IPC group(IPC ﹢ IR group),sham IPC group(S ﹢ IR group),all groups were randomly divided into 9 sub groups(0 h,3 h,6 h,12 h,24 h,48 h,3 d,5 d,7 d)except C group according to the time points after reperfusion. Occurrence of apoptosis was detected by terminal deoxynuleotidyl transferase media-ted dUTP nick end and labeling(TUNEL)method;the mRNA expression and protein levels of Bax and Bcl - 2 were de-tected by reverse transcriptase - polymerase chain reaction and quantitave immunohistochemisty. Results (1)Com-pared with S group and S ﹢ IR group,serum creatinine,blood urea nitrogen,kidney pathological damage scores in IR group gradually increased after IR,and peak point was 24 h after reperfusion;among all the subgroups there was a sig-nificant difference(all P ﹤ 0. 01). The expression of Bax,Bcl - 2 mRNA raised sharply in IR group after reperfusion, peaking at 6 h,24 h of reperfusion respectively,2. 66 ± 0. 12,2. 70 ± 0. 10,and among all the subgroups there was a sig-nificant difference(all P ﹤ 0. 01);the expression of Bax,Bcl - 2 protein had significant difference(all P ﹤ 0. 05). TUNEL immunofluorescence staining showed C group and S group had no obvious apoptosis cells in renal tubular epi-thelium;epithelial cell apoptosis after IR gradually increased in IR group,peaking at 24 h of reperfusion[(25. 07 ± 2. 29)% ].(2)Compared with IR group and S ﹢ IR group,pathological injury was significantly decreased in IPC ﹢ IR group;the expression of Bax,Bcl - 2 mRNA and protein,apoptosis cells were significantly decreased in IPC ﹢ IR group (all P ﹤ 0. 05). Conclusions Bax,Bcl - 2 are closely associated with kidney injury induced by IR. IPC may regulate acute kidney injuries by regulating Bax/ Bcl - 2.

Expression of tight junction protein claudin-2 in renal tissues and its significance in children with acute kidney injury / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To examine changes in expression of tight junction protein claudin-2 in the renal tissues of children with acute kidney injury (AKI), and to investigate the relationship of claudin-2 expression with renal pathological lesion and renal functional lesion.</p><p><b>METHODS</b>Twenty-four children who were diagnosed with AKI and had renal biopsies between December 2009 and December 2011 were included in the study. These patients were divided into mild AKI (n=7) and severe AKI groups (n=17). Children with isolated hematuria whose renal biopsy showed minor glomerular lesion were selected as the control group. Serum creatinine levels were measured by automatic biochemical analyzer. Tubulointerstitial damage was evaluated by renal pathological scores and expression of claudin-2 was examined by immunohistochemistry. The correlations of claudin-2 expression with renal pathological score and serum creatinine level were assessed by Pearson correlation analysis.</p><p><b>RESULTS</b>The mild and severe AKI groups had significantly higher serum creatinine levels than the control group (190 ± 68 μmol/L and 477 ± 128 μmol/L vs 29 ± 7 μmol/L, P<0.01), and the severe AKI group had a significantly higher serum creatinine level than the mild AKI group (P<0.01). The tubulointerstitial damage score was significantly lower in the mild AKI group than in the severe AKI group (10.4 ± 1.7 vs 14.0 ± 1.5; P<0.05). The mild and severe AKI groups had significantly smaller areas of claudin-2 expression than the control group (5.0 ± 0.5% and 3.7 ± 0.7% vs 8.0 ± 0.7%; P<0.01), and the severe AKI group had a significantly smaller area of claudin-2 expression than the mild AKI group (P<0.01). The area of claudin-2 expression was negatively correlated with serum creatinine level and tubulointerstitial damage score (r=-0.809 and -0.903; P<0.01).</p><p><b>CONCLUSIONS</b>There are changes in the distribution and expression of claudin-2 in proximal tubular epithelial cells among children with AKI, and claudin-2 expression is closely related to renal pathological lesion and renal functional lesion.</p>

MicroRNA-21-5p regulating p38 mitogen-activated protein kinases signaling pathway / 中华实用儿科临床杂志

Objective To verify the targeting regulatory relationship between microRNA (miR)-21-5p and mitogen-activated protein kinase kinase 3 (MKK3).Methods miR-21-5p and MKK3 targeted relationship was analyzed by bioinformatics database predict.Constructing MKK3 3'UTR reporter vector (MKK3-3U) and mutation reporter vector (MKK3-3 U-M) was constructed by synthesizing miR-21-5p mimics (mimic),miR-2 1-5p inhibitor (inhibitor),nonsense miR (NC).NC (NC1 group),mimics (mimic1 group),inhibitor (inhibitor1 group) together with MKK3-3U cotransfected human embryonic kidney (HEK293) cells,respectively.Empty vector-pYr-MirTarget (NC2 group),MKK33U (Mt group),M KK3-3U-M (Mut group) together with mimic co-transfected HEK293,respectively.The fluorescence ratio was detected by dual luciferase assay.NC,mimics,inhibitor intervened human renal tubular epithelial (HK-2) cells,respectively.RT-PCR and Western blot were used to test cell MKK3 expression level in HK-2.Results 1.The fluorescence ratios of NC1 group,mimicsl group,and inhibitor1 group were 100.00％,67.99％,133.17％,and there was difference between mimic1 group and NC1 group(t =19.93,P ＜ 0.05).2.The fluorescence ratios of NC2 group,Mt group and Mut group were 100.00％,65.30％,98.48％,and there was difference between Mt group and NC2 group (t =14.39,P ＜ 0.05).There was no significant difference between NC2 and Mut group (t =0.63,P ＞ 0.05).3.MKK3 mRNA relative expression levels of the control group mimic2 group and inhibitor2 group were 1.36 ± 0.02,1.01 ± 0.04,1.43 ± 0.06 ; relative protein expression levels were 0.97 ± 0.05,0.62 ± 0.06,1.36 ± 0.32.MKK3 mRNA and protein levels of mimic2 group were significantly lower compared with the control group (F =85.98,118.26,all P ＜ 0.01).Conclusions MKK3 is the target gene of miR-21-5p.miR-21-5p can regulate the expression of MKK3 both in mRNA and protein levels.miR-21-5p may be an important regulatory molecule in p38 mitogen-activated protein kinase signaling pathway.

Bacteria Distribution of Clinical Specimen and Drug Resistance Analysis / 中华医院感染学杂志

OBJECTIVE To investigate the clinicl bacteria distribution and the drug resistance.METHODS The biochemical and serologic tests were used to detect the susceptibility of bacterium to antimicrobials.RESULTS The positive rate was 44.87%,bacteria distributed mainly in sputum,urine and secretion.Pseudomonas aeruginosa,Escherichia coli,Staphylococcus epidermidis,Klebsiella pneumoniae and Acinetobacter often appeared.The drug resistance rate of MRSA and MRCNS was higher than MSSA and MSCNS's.The drug sensitive rate of Enterococcus faecium was less than E faecalis's.Bacteria of Enterobacteriaceae were sensitive to the drug of imipenem.The test rate for E.coli and K.pneumoniae which released ESBLs was 23.9% and 25.4%,respectively.P.aeruginosa possessed high resistance to all drugs.CONCLUSIONS The rate of Gram-positive cocci in all specimen is rising,the drug resistance is rather related with the broad use of antimicrobials.

Expression of the soluble human Fas ligand in Dictyostelium discoideum / 生物工程学报

An expression system is described for high-yield production of recombinant soluble human FasL (shFasL) in Dictyostelium discoideum cells. DNA encoding amino acids 141 - 281 of hFasL was PCR amplified from cDNA derived from activated human neutrophils. The resulting product was fused with a DNA fragment encoding hCG-beta signal peptide and cloned in the expression vector pMB12neo. Dictyostelium strain AX3 was transfected with this plasmid, yielding a recombinant strain called AX3-pCESFL95-H3. In order to improve the shFasL expression level, pMB12neo was optimized by replacing its transcriptional terminator/ polyadenylation segment of the 2H3 gene with an actin8 terminator/polyadenylation segment, yielding derived expression vector pMB74. The recombinant Dictyostelium strain called AX3-pLu8 was generated with this new plasmid. When the recombinant cells were cultivated in a complex HL-5C medium, a cell density of (1.5 - 2) x 10(7)/mL was reached, and the shFasL level expressed by strains AX3-pCESFL95-H3 and AX3-pLu8 was 23.5 microg/L and 206 microg/L, respectively. By using a newly developed synthetic medium called SIH as culture medium, higher cell density of (4 - 5) x 10(7)/mL was achieved. Correspondently, 111 microg/L and 420 microg/L shFasL were secreted by recombinant strains AX3-pCESFL95-H3 and AX3-pLu8, respectively.

Influence of Liang-Xue-Huo-Xue (LXHX) Capsule on Apoptosis of Cultured Keratinocytes / 中华皮肤科杂志

Objective To investigate the pharmacological mechanism of LXHX capsule. Methods The skin specimens from psoriasis patients were examined with TUNEL (terminal deoxynucleotidyl trans-ferase-mediated dUTP-biotin nick end labeling) technique to detect the apoptosis of keratinocytes. PCNA (proliferating cell nuclear antigen) detecting kits was used, too. Then, the flow cytometry, with AnnexinV/PI and PI dyeing method, was used to analysis the effect of LXHX capsule on apoptosis in cultured keratinocytes. Results There was an increasing of both cell apoptosis and proliferation in psoriatic epidermis and LXHX capsule could induce apoptosis. Conclusions The keratinocyte apoptosis and proliferation both increased in psoriasis, which reach a new balance in a higher level. LXHX capsule could induce apoptosis in vitro, which may be one of the pharmacological mechanisms of LXHX in treating psoriasis.

Uptake of nickel from industrial wastewater by genetically engineered Escherichia coli JM109 / 生物工程学报

Heavy metal wastewater poses a serious threat to the environment. In comparison to the existing methods of chemical precipitation, ion exchange and carbon adsorption, biosorption is an attractive alternative for the recovery of heavy metals from industrial effluents. However, nickel ion, different from other heavy metal ions, is a more recalcitrant pollutant and has low affinity to many metal tolerant microorganisms. In this study, Escherichia coli JM109 was genetically engineered to simultaneously express a Ni2+ transport system (the product of nixA gene) andoverexpress metallothionein (MT). NixA protein has a high affinity for Ni2+, and metallothioneins (MTs) are capable of binding a variety of heavy metals including Ni2+ . The Ni2+ bioaccumulation performance of the genetically engineered E. coli JM109 was evaluated. Time-course test showed that the bioaccumulation rate was rapid, and 95% of the accumulation was achieved within the first 10 minutes. The maximum Ni2+ bioaccumulation by genetically engineered E. coli cells was dramatically increased from 1.54 mg/g to 10.11mg/g, a more than five-fold increase than that of the original E. coli strain. The isotherm was of Langmuir type. Within the tested pH range (pH 4-10), the engineered cells displayed more resistance to pH variation, retaining up to 80% of the Ni2+ binding capacity at pH 4, while the original E. coli host cells lost 80% of Ni2+ binding capacity at pH 4. The presence of Na+ and Ca2+ affected Ni2+ bioaccumulation, but the effects were not serious, as 71% and 66% of the Ni2+ binding capacities were retained respectively at the concentrations of 1000 mg/L Na+ and 1000 mg/L Ca2+ . However, Mg2+ exerted a severe adverse effect on Ni2+ bioaccumulation, 83% of Ni2+ accumulating capacity was lost when Mg2+ concentration reached 200 mg/L. The effects of different kinds of heavy metals on Ni2+ accumulating were different. The genetically engineered E. coli cell lost less than 45% of its Ni2+ bioaccumulation activity in the presence of 50 mg/L lead or cadmium, 66% in the presence of 25mg/L mercury and 84% in the presence of 40 mg/L copper. The presence of glucose did not improve Ni2+ uptake. Our study suggests that the genetically engineered E. coli JM109 has potential application for effective and efficient recovery of nickel from aqueous solutions.