Although metal blocks have been widely used for reconstructing uncontained tibial bone defects, the influence of their elastic modulus on the stability of tibial prosthesis fixation remains unclear. Based on this, a finite element model incorporating constrained condylar knee (CCK) prosthesis, tibia, and metal block was established. Considering the influence of the post-restraint structure of the prosthesis, the effects of variations in the elastic modulus of the block on the von Mises stress distribution in the tibia and the block, as well as on the micromotion at the bone-prosthesis fixation interface, were investigated. Results demonstrated that collision between the insert post and femoral prosthesis during tibial internal rotation increased tibial von Mises stress, significantly influencing the prediction of block elastic modulus variation. A decrease in the elastic modulus of the metal block resulted in increased von Mises stress in the proximal tibia, significantly reduced von Mises stress in the distal tibia, decreased von Mises stress of the block, and increased micromotion at the bone-prosthesis fixation interface. When the elastic modulus of the metal block fell below that of bone cement, inadequate block support substantially increased the risk of stress shielding in the distal tibia and fixation interface loosening. Therefore, this study recommends that biomechanical investigations of CCK prostheses must consider the post-constraint effect, and the elastic modulus of metal blocks for bone reconstruction should not be lower than 3 600 MPa.
Knee Prosthesis ; Humans ; Finite Element Analysis ; Tibia/surgery* ; Elastic Modulus ; Arthroplasty, Replacement, Knee/methods* ; Stress, Mechanical ; Metals ; Prosthesis Design ; Knee Joint/surgery* ; Biomechanical Phenomena

Objective: To identify the main metals involved in cognitive impairment in the Chinese oldest old, and explore the association between these metal exposures and cognitive impairment. Methods: A cross-sectional study was conducted on 1 568 participants aged 80 years and older from Healthy Aging and Biomarkers Cohort Study (2017 to 2018). Fasting venous blood was collected to measure the levels of nine metals (selenium, lead, cadmium, arsenic, antimony, chromium, manganese, mercury, and nickel). The cognitive function of these participants was evaluated by using the Chinese version of the Mini-Mental State Examination (CMMSE). The random forest (RF) was applied to independently identify the main metals that affected cognitive impairment. The multivariate logistic regression model and restricted cubic splines (RCS) model were used to further verify the association of the main metals with cognitive impairment. Results: The age of 1 568 study subjects was (91.8±7.6) years old, including 912 females (58.2%) and 465 individuals (29.7%) with cognitive function impairment. Based on the RF model (the out-of-bag error rate was 22.9%), the importance ranking of variables was conducted and the feature screening of five times ten-fold cross-validation was carried out. It was found that selenium was the metal that affected cognitive function impairment, and the other eight metals were not included in the model. After adjusting for covariates, the multivariate logistic regression model showed that with every increase of 10 μg/L of blood selenium levels, the risk of cognitive impairment decreased (OR=0.921, 95%CI: 0.889-0.954). Compared with the lowest quartile(Q₁) of blood selenium, the ORs (95%CI) of Q₃ and Q₄ blood selenium were 0.452 (0.304-0.669) and 0.419 (0.281-0.622) respectively. The RCS showed a linear dose-response relationship between blood selenium and cognitive impairment (P_nonlinear>0.05). Conclusion: Blood selenium is negatively associated with cognitive impairment in the Chinese oldest old.
Aged, 80 and over ; Female ; Humans ; Selenium ; Cohort Studies ; Cross-Sectional Studies ; Metals/analysis* ; Cognitive Dysfunction/epidemiology* ; China/epidemiology*

A microbial fuel cell (MFC)-based microbial electrochemical sensor was developed for real-time on-line monitoring of heavy metals in water environment. The microbial electrochemical sensor was constructed with staggered flow distribution method to optimize the parameters such as external resistance value and external circulation rate. The inhibition of concentration of simulated heavy metal wastewater on voltage under optimal parameters was analyzed. The results showed that the best performance of MFC electrochemical sensor was achieved when the external resistance value was 130 Ω and the external circulation rate was 1.0 mL/min. In this case, the microbial electrochemical sensors were responsive to 1-10 mg/L Cu²⁺, 0.25-1.25 mg/L Cd²⁺, 0.25-1.25 mg/L Cr⁶⁺ and 0.25-1.00 mg/L Hg²⁺ within 60 minutes. The maximum rejection rates of the output voltage were 92.95%, 73.11%, 82.76% and 75.80%, respectively, and the linear correlation coefficients were all greater than 0.95. In addition, the microbial electrochemical sensor showed a good biological reproducibility. The good performance for detecting heavy metals by the newly developed microbial electrochemical sensor may facilitate the real-time on-line monitoring of heavy metals in water environment.
Bioelectric Energy Sources ; Electrodes ; Metals, Heavy/analysis* ; Reproducibility of Results ; Waste Water ; Water

In this study, the content of five heavy metals(Pb, Cd, As, Hg, and Cu) in 59 batches of Lonicerae Japonicae Flos(LJF) medicinal materials and pieces were determined by inductively coupled plasma mass spectrometry(ICP-MS). The health risk assessment was processed using the maximum estimated daily intake(EDI), target hazard quotients(THQ), and carcinogenic risks(CR) assessment models. With reference to the limit standard for heavy metal content in LJF specified in 2020 edition of Chinese Pharmacopoeia, five batches produced in Hebei were found to contain excessive Pb, and the remaining 54 batches met the specifications, with the unqualified rate of 8.47%. Comparative analysis of heavy metal content in LJF samples from three different producing areas, namely Shandong, Henan, and Hebei showed that the levels of Pb, As, and Hg in LJF from Hebei were significantly higher than those from Henan and Shandong. The samples produced in Shandong contained the highest content of Cd. The samples from Hebei contained the highest content of Cu while those from Shandong had the lowest content of Cu. As demonstrated by health risk assessment based on the EDI, THQ and CR models, these 59 batches of LJF samples did not cause significant health hazards for the exposed population, and there was no potential non-carcinogenic or carcinogenic risk. In conclusion, a few of LJF samples contained excessive heavy metals, so some measures, including controlling production environment, cultivating management mode, and optimizing processing methods, should be taken for ensuring the medication safety of LJF.
Drugs, Chinese Herbal ; Environmental Pollution/analysis* ; Mercury/toxicity* ; Metals, Heavy/toxicity* ; Risk Assessment

OBJECTIVES: To study the association of the levels of heavy metals and trace elements during pregnancy with congenital heart defects (CHD) in offspring, and to establish a model for predicting the probability of CHD based on the levels of heavy metals and trace elements during pregnancy. METHODS: Based on the prospective birth cohort study in Gansu Provincial Maternal and Child Health Hospital in 2010-2012, a nested case-control study was conducted for the follow-up observation of 14 359 pregnant women. Among the pregnant women, 97 pregnant women whose offspring were diagnosed with CHD during follow-up were enrolled as the CHD group, and 194 pregnant women whose offspring had no CHD were selected as the control group. Inductively coupled plasma mass spectrometry was used to measure the levels of heavy metals and trace elements in maternal blood samples and fetal umbilical cord blood samples. A multivariate logistic regression analysis was used to evaluate the association between heavy metal and trace elements and CHD in offspring. A nomogram model for predicting the probability of CHD in offspring was established based on the levels of heavy metals and trace elements during pregnancy. RESULTS: Compared with the control group, the CHD group had significantly higher levels of aluminum (Al), natrium (Na), calcium (Ca), titanium (Ti), selenium (Se), strontium (Sr), stannum (Sn), stibium (Sb), barium (Ba), and thorium (Th) in maternal blood samples (P<0.05), as well as significantly higher levels of Al, zinc (Zn), magnesium (Mg), kalium (K), Ca, Ti, chromium (Cr), copper (Cu), arsenic (As), Se, Sr, argentum (Ag), cadmium (Cd), Sn, and plumbum (Pb) in umbilical cord blood (P<0.05). The multivariate logistic regression analysis showed that the increase in the Sb level in maternal blood was associated with the increase in the risk of CHD in offspring [adjusted odds ratio (^aOR)=4.81, 95% confidence interval (CI): 1.65-14.07, P=0.004], while in umbilical cord blood, the high levels of Al (^aOR=4.22, 95%CI: 1.35-13.16, P=0.013), Mg (^aOR=8.00, 95%CI: 1.52-42.08, P=0.014), and Pb (^aOR=3.82, 95%CI: 0.96-15.23, P=0.049) were significantly associated with the risk of CHD in offspring. The levels of Al, Th, and Sb in maternal blood and levels of Al, Mg, and Pb in umbilical cord blood were included in the predictive model for CHD in offspring based on the levels of heavy metals and trace elements during pregnancy, and the calibration curve of the nomogram predictive model was close to the ideal curve. CONCLUSIONS Increases in the levels of Al, Th, Sb, Mg, and Pb during pregnancy may indicate the increase in the risk of CHD in offspring, and the nomogram predictive model based on these indices can be used to predict the probability of CHD in offspring.
Case-Control Studies ; Child ; Cohort Studies ; Female ; Heart Defects, Congenital/etiology* ; Humans ; Metals, Heavy ; Pregnancy ; Prospective Studies ; Trace Elements/analysis*

The effects of four natural organic soil amendments on the quality and pesticide residues of Panax notoginseng were investigated through field experiments and the suitable dosage ratio of each soil amendment was selected to provide a new idea for the pollution-free cultivation of P. notoginseng. The four natural organic soil amendments used in this study were Jishibao, Jihuo, Fudujing, and omnipotent nutrients, which were produced by mixed fermentation of aboveground parts of different plants, biological waste residue, and biochar. During the experiments, only four soil amendments were applied to P. notoginseng instead of any pesticides and fertilizers. The experiment was designed as four factors and three levels. There were three dosage gradients(low, medium, and high) for Jishibao(A), Jihuo(B), Fudujing(C), and omnipotent nutrients(D). When the dosage of one soil amendment changed, the do-sage of the other soil amendments remained medium. There were 10 groups in addition to the soil amendment-free group as control(CK). The results showed that the four soil amendments could significantly improve the growth environment of P. notoginseng and increase the seedling survival rate and saponin content of P. notoginseng. The seedling survival rates of the treatment groups increased by 8.24%-30.05% as compared with the control group. Furthermore, the content of pesticide residues in P. notoginseng was too low to be detected, and that of heavy metals in P. notoginseng was far lower than the specified content in the Chinese Pharmacopoeia(2020). The optimal effect was achieved at medium dosage for all the soil amendments with the highest content of saponins, high seedling survival rate, and significantly reduced heavy metals, such as lead, cadmium, arsenic, and mercury.
Arsenic ; Metals, Heavy/analysis* ; Panax notoginseng ; Soil ; Soil Pollutants/analysis*

Objective: This study aimed to assess the risk of cumulative exposure to Pb, Cd, Hg, and iAs through aquatic products consumed by Chinese people. Methods: Heavy metal concentration data were obtained from the national food contamination monitoring program during 2013-2017. Consumption data were derived from the China National Food Consumption Survey in 2014 and the relative potency factor (RPF) method was used to estimate cumulative exposure for neurotoxicity and nephrotoxicity. Results: The results demonstrated that the cumulative exposure based on neurotoxicity was below the lower confidence limit on benchmark doses of lead (BMDL Conclusion The cumulative exposures of the 2-6 year-old group to the four heavy metals did not reach (but came close to) the corresponding safety threshold for both neurotoxicity and nephrotoxicity. Given that there are still other food sources of these four heavy metals, it is necessary to more closely study their cumulative health effects.
Adolescent ; Adult ; Aged ; Animals ; Arsenic/analysis* ; Child ; Child, Preschool ; Dietary Exposure/analysis* ; Environmental Monitoring ; Food Contamination/analysis* ; Humans ; Metals, Heavy/analysis* ; Middle Aged ; Risk Assessment ; Seafood/analysis* ; Water Pollutants, Chemical/analysis* ; Young Adult

Aged ; Biological Monitoring ; Female ; Femur/chemistry* ; Humans ; Knee Joint/chemistry* ; Male ; Meniscus/chemistry* ; Metals/analysis* ; Middle Aged ; Tibia/chemistry*

Aiming at the phenomenon of heavy metal Cd exceeding the standard of Chuanxiong medicinal materials,the accumulation of 12 inorganic elements,including heavy metals,in Ligusticum chuanxiong was studied in this paper. It was found that the contents and distribution of most inorganic elements in the stems and leaves of L. chuanxiong were higher than those in the rhizomes at seedling and shooting stages. The content of most elements in rhizome reached the highest at harvest stage,and the distribution ratio of some elements in rhizome was higher than that in stem and leaf at harvest stage. But rhizome,stem and leaf of L. chuanxiong have relatively stable absorption capacity and enrichment effect on different elements,and are less affected by growth period and position. Rhizomes and stems and leaves of L. chuanxiong were enriched with Cd,and stems and leaves also accumulated Pb at seedling stage and stem stage. The absorption capacity of Pb in stems and leaves of L. chuanxiong was higher than that of rhizomes,and the ability of absorbing Cd was less than that of rhizomes at harvest time. The total uptake of Cd and Pb by L. chuanxiong decreased with the prolongation of growth time,but the proportion of Cd and Pb in rhizome increased,so that the content of Cd and Pb increased with the prolongation of growth time.
Cadmium ; analysis ; Drugs, Chinese Herbal ; chemistry ; Ligusticum ; chemistry ; Metals, Heavy ; analysis ; Plant Leaves ; chemistry ; Plant Stems ; chemistry ; Rhizome ; chemistry

To evaluate the safety of heavy metals contaminated Astragalus membranaceus,an appropriate protocol was established to study the heavy metals pollution level by health risk assessment. This study provided a detailed procedure to assess the medicinal herbs in quality control and safety evaluation,and expected to create awareness among the public on the safety of consuming of A. membranaceus or any other kinds of medicinal herbs. The heavy metals content of Cu,As,Cd,Pb and Hg in a total of 45 batches of A. membranaceus were carefully analyzed with a developed inductively coupled plasma mass spectrometry( ICP-MS). Besides,the heavy metal contamination level was further evaluated through 4 main assessment parameters,including maximum residue limit( MRL) set by International Standard Organization,estimated daily intake( EDI) set by IUPAC,target hazard quotients( THQ) and Total THQ set by USEPA and total THQs in raw herbs of A. membranaceus. In addition,the recommended MRLs of 5 main heavy metals aimed to A. membranaceus were calculated based on the regulated consumption quantity. The result showed that,under the ISO international standard of Chinese medicine-Chinese herbal medicine heavy metals,the unqualified rate was 8. 89% for A. membranaceus,which including 4 batches of A. membranaceus exceeded the MRL of As. Here,the standard THQ value of A. membranaceus was firstly proposed as 0. 02 and 0. 011 25 for adults and children,respectively,which were calculated with the recommended consumption quantity of 30 g and 9 g for adults and children. Furthermore,the values of THQ for As and total THQs in adults and children were exceeded the standard THQ in A. membranaceus,and the recommended MRLs of Pb,Cd,Hg and Cu in above medicinal materials that calculated based on health risk assessment model were higher than the regulated MRLs that set by ISO and Chinese Pharmacopeia. The research showed that the contents of heavy metals in A. membranaceus were not in the safe range and the certain non-carcinogenic risks to human body cannot be neglected. Based on above investigation result,it is easily known that the common evaluation method for raw herbs based on the comparison of MRL of heavy metals was not precise enough,and the international model of health risk assessment should be built for each medicinal herb. Above all,this study provided a more realistic research approach for safety evaluation of any other kinds of heavy metals contaminated medicinal herbs,including the establishment of heavy metals standard limit in a specified medicinal herb under recommended consumption quantity,and it is expected to create awareness among the public on the safety of consuming any other medicinal herbs.
Astragalus propinquus ; chemistry ; Drug Contamination ; Drugs, Chinese Herbal ; analysis ; standards ; Humans ; Metals, Heavy ; analysis ; Plants, Medicinal ; chemistry ; Risk Assessment