[Finite element analysis of the impact of bone mass and volume of low-density area under tibial plateau on lower limb alignment].

Objective: To investigate the impact of the bone mass and volume of the low-density area under the tibial plateau on the lower limb force line by finite element analysis, offering mechanical evidence for preventing internal displacement of the lower limb force line in conjunction with knee varus in patients with knee osteoarthritis (KOA) and reducing bone mass under the tibial plateau. Methods: A healthy adult was selected as the study subject, and X-ray film and CT imaging data were acquired. Mimics 21.0 software was utilized to reconstruct the complete knee joint model and three models representing low-density areas under the tibial plateau with equal volume but varying shapes. These models were then imported into Solidworks 2023 software for assembly and verification. Five KOA finite element models with 22%, 33%, 44%, 55%, and 66% bone mass reduction in the low-density area under tibial plateau and 5 KOA finite element models with 81%, 90%, 100%, 110%, and 121% times of the low-density area model with 66% bone mass loss were constructed, respectively. Under physiological loading conditions of the human lower limb, the distal ends of the tibia and fibula were fully immobilized. An axial compressive load of 1 860 N, following the lower limb force line, was applied to the primary load-bearing area on the femoral head surface. The maximum stress within the tibial plateau, as well as the maximum displacements of the tibial cortical bone and tibial subchondral bone, were calculated and analyzed using the finite element analysis software Abaqus 2022. Subsequently, predictions regarding the alteration of the lower limb force line were made based on the analysis results. Results: The constructed KOA model accorded with the normal anatomical structure of lower limbs. Under the same boundary conditions and the same load, the maximum stress of the medial tibial plateau, the maximum displacement of the tibial cortical bone and the maximum displacement of the cancellous bone increased along with the gradual decrease of bone mass in the low-density area under the tibial plateau and the gradual increase in the volume of the low-density area under tibial plateau, with significant differences ( P<0.05). Conclusion: The existence of a low-density area under tibial plateau suggests a heightened likelihood of knee varus and inward movement of the lower limb force line. Both the volume and reduction in bone mass of the low-density area serve as critical initiating factors. This information can provide valuable guidance to clinicians in proactively preventing knee varus and averting its occurrence.

[Finite element analysis for predicting osteonecrosis of the femoral head collapse based on the preserved angles].

Objective: To establish finite element models of different preserved angles of osteonecrosis of the femoral head (ONFH) for the biomechanical analysis, and to provide mechanical evidence for predicting the risk of ONFH collapse with anterior preserved angle (APA) and lateral preserved angle (LPA). Methods: A healthy adult was selected as the study object, and the CT data of the left femoral head was acquired and imported into Mimics 21.0 software to reconstruct a complete proximal femur model and construct 3 models of necrotic area with equal volume and different morphology, all models were imported into Solidworks 2022 software to construct 21 finite element models of ONFH with LPA of 45°, 50°, 55°, 60°, 65°, 70°, and 75° when APA was 45°, respectively, and 21 finite element models of ONFH with APA of 45°, 50°, 55°, 60°, 65°, 70°, 75° when LPA was 45°, respectively. According to the physiological load condition of the femoral head, the distal femur was completely fixed, and a force with an angle of 25°, downward direction, and a magnitude of 3.5 times the subject's body mass was applied to the weight-bearing area of the femoral head surface. The maximum Von Mises stress of the surface of the femoral head and the necrotic area and the maximum displacement of the weight-bearing area of the femoral head were calculated and observed by Abaqus 2021 software. Results: The finite element models of ONFH were basically consistent with biomechanics of ONFH. Under the same loading condition, there was stress concentration around the necrotic area in the 42 ONFH models with different preserved angles composed of 3 necrotic areas with equal volume and different morphology. When APA was 60°, the maximum Von Mises stress of the surface of the femoral head and the necrotic area and the maximum displacement of the weight-bearing area of the femoral head of the ONFH models with LPA<60° were significantly higher than those of the models with LPA≥60° ( P<0.05); there was no significant difference in each index among the ONFH models with LPA≥60° ( P>0.05). When LPA was 60°, each index of the ONFH models with APA<60° were significantly higher than those of the models with APA≥60° ( P<0.05); there was no significant difference in each index among the ONFH models with APA≥60° ( P>0.05). Conclusion: From the perspective of biomechanics, when a preserved angle of ONFH is less than its critical value, the stress concentration phenomenon in the femoral head is more pronounced, suggesting that the necrotic femoral head may have a higher risk of collapse in this state.

Correction to: Characteristic of microplastics in the atmospheric fallout from Dongguan City, China: preliminary research and first evidence.

Unfortunately, the original version of this article contained two mistakes.

Characteristic of microplastics in the atmospheric fallout from Dongguan city, China: preliminary research and first evidence.

Microplastic pollution has exhibited a global distribution, including seas, lakes, rivers, and terrestrial environment in recent years. However, little attention was paid on the atmospheric environment, though the fact that plastic debris can escape as wind-blown debris was previously reported. Thus, characteristics of microplastics in the atmospheric fallout from Dongguan city were preliminarily studied. Microplastics of three different polymers, i.e., PE, PP, and PS, were identified. Diverse shapes of microplastics including fiber, foam, fragment, and film were found, and fiber was the dominant shape of the microplastics. SEM images illustrated that adhering particles, grooves, pits, fractures, and flakes were the common patterns of degradation. The concentrations of non-fibrous microplastics and fibers ranged from 175 to 313 particles/m2/day in the atmospheric fallout. Thus, dust emission and deposition between atmosphere, land surface, and aquatic environment were associated with the transportation of microplastics.

Microplastics in the surface sediments from the Beijiang River littoral zone: Composition, abundance, surface textures and interaction with heavy metals.

While large quantities of studies on microplastics in the marine environment have been widely carried out, few were available in the freshwater environment. The occurrence and characteristics, including composition, abundance, surface texture and interaction with heavy metals, of microplastics in the surface sediments from Beijiang River littoral zone were investigated. The concentrations of microplastics ranged from 178 ± 69 to 544 ± 107 items/kg sediment. SEM images illustrated that pits, fractures, flakes and adhering particles were the common patterns of degradation. Chemical weathering of microplastics was also observed and confirmed by µ-FTIR. EDS spectra displayed difference in the elemental types of metals on the different surface sites of individual microplastic, indicating that some metals carried by microplastics were not inherent but were derived from the environment. The content of metals (Ni, Cd, Pb, Cu, Zn and Ti) in microplastics after ultrasonic cleaning has been analyzed by ICP-MS. Based on data from the long-term sorption of metals by microplastics and a comparison of metal burden between microplastics, macroplastics and fresh plastic products, we suggested that the majority of heavy metals carried by microplastics were derived from inherent load.

Sorption of 3,3',4,4'-tetrachlorobiphenyl by microplastics: A case study of polypropylene.

Though plastics show good chemical inertness, they could sorb polychlorinated biphenyls (PCBs) and other toxic pollutants from the surrounding environment. Thus, ingestion of microplastics by marine organisms potentially enhances the transport and bioavailability of toxic chemicals. However, there is lack of studies on the sorption capacity, mechanism and factors affecting the sorption behavior. Here, sorption of PCBs by microplastics in the simulated seawater was studied using the batch oscillation equilibration technique, in which polypropylene (PP) and 3,3',4,4'-tetrachlorobiphenyl (PCB77) acted as model plastic and PCB, respectively. Factors including particle size, temperature and solution environment were investigated. Results showed that, equilibrium sorption time is about 8h and sorption capacity increase with decreasing particle size and temperature. Different sorption capacity in three solution environments was observed. Equilibrium data in three solution environments fitted very well to the Langmuir sorption model, indicating chemical sorption is the predominant mechanism.

[Pollution Characteristics and Ecological Risk Assessment of Organochlorine Pesticides in Water Source Areas of Guangdong and Guangxi].

The concentrations of 16 organochlorine pesticides (OCPs) in 7 water samples collected from different sites of water source areas of Guangdong and Guangxi were detected by SPE-GC-MS, and then the pollution characteristics were analyzed. This study established species sensitivity distribution(SSD) curves with BurrⅢ distribution model. In the meantime, HC5 values were calculated by BurrliOZ software, which were used to evaluate the toxicity effects of OCPs towards aquatic organisms. Finally, margin of safety concentration values were calculated to assess the ecological risk. The results showed that the concentration of OCPs varied from 6.64 to 34.19 ng·L-1, with a mean value of 16.76 ng·L-1, while HCHs and DDTs contributed a lot. HCHs were predominately originated from lindane, which is a component in household insecticide, while DDTs were from dicofol contamination or historical residues. Vertebrates could stand severer toxicity in comparison with invertebrates. α-endosulfan showed a greater toxicity towards aquatic plants and microorganisms than others, while p, p'-DDT turned out to be the most hazardous pollutant to vertebrates and invertebrates among the 16 OCPs studied. Generally speaking, OCPs in study areas didn't show conspicuous ecological risks towards aquatic organisms, DDTs and α-endosulfan, however, are still worth paying close attention due to their high potential risks.

Cinnamon extract lowers glucose, insulin and cholesterol in people with elevated serum glucose.

Cinnamon ( ròu guì) has in vitro insulin potentiating activity, and proanthocyanidins from cinnamon prevent in vitro formation of advanced glycation end products. Some human studies were equivocal, but several have shown beneficial effects of cinnamon supplementation on circulating glucose, lipids, and/or insulin. This placebo-controlled double-blind trial tested the effects of a dried water extract of cinnamon (Cinnamomum cassia) on circulating glucose, lipids, insulin, and insulin resistance. Men and women from Beijing and Dalian, China, were invited to participate if they had fasting serum glucose >6.1 mmol/L or 2-h glucose >7.8 mmol/L. Participants, (173 were enrolled and 137 completed the study) were randomly assigned to receive either a spray-dried, water extract of cinnamon (CinSulin®), 250 mg/capsule, or a placebo, twice a day for two months. Mean ± SEM age of participants was 61.3 ± 0.8 years, BMI was 25.3 ± 0.3 and M/F ratio was 65/72. After 2 mo, fasting glucose decreased (p < 0.001) in the cinnamon extract-supplemented group (8.85 ± 0.36 to 8.19 ± 0.29 mmol/L) compared with the placebo group (8.57 ± 0.32 to 8.44 ± 0.34 mmol/L, p = 0.45). Glucose 2 h after a 75 g carbohydrate load, fasting insulin, and HOMA-IR also decreased with cinnamon extract compared with placebo. Total and LDL-cholesterol decreased with cinnamon extract and HDL-cholesterol decreased in both the cinnamon-extract and placebo groups. In conclusion, supplementation with 500 mg of water-extract of cinnamon for two months reduced fasting insulin, glucose, total cholesterol, and LDL cholesterol and enhanced insulin sensitivity of subjects with elevated blood glucose.

[Analysis of endemic situation of schistosomiasis in Yugan County of Jiangxi Province in 2012].

OBJECTIVE: To master the epidemic situation and control effect of schistosomiasis in Yugan County, Jiangxi Province. METHODS: The data of the schistosomiasis prevalence in human and cattle as well as Oncomelania hupensis snail status were collected and the change trends were analyzed in Yugan County from 2008 to 2012. RESULTS: The schistosome infection rates of residents in Yugan County have declined every year since 2008, and currently, the prevalence of schistosomiasis was at a low level. No acute schistosomiasis case was found during the past 5 years. In 2012, the infection rate of bovine was above 1% in 88 endemic villages, and the area with schistosome infected snails was 10 hm2. CONCLUSION: In order to achieve the goal of schistosomiasis transmission control in the whole county in 2015, the comprehensive control measures based on infection source control should be strengthened.

[Effects of teriparatide and alendronate on bone mineral density of osteoporotic rats].

OBJECTIVE: To investigate the effects of teriparatide (hPTH1-34, PTH) and alendronate (Alen) on bone turnover rate and bone mineral density (BMD) of ovariectomized (OVX) osteoporotic rats. METHODS: 70 female 6-month-old Wistar rats were randomly divided into 7 groups: (1) baseline group: killed immediately as baseline controls; (2) sham operation group: injected subcutaneously with normal saline (NS) as normal controls; (3) OVXb group: underwent ovarietomy (OVX) and killed 6 weeks after OVX as pre-therapeutic controls; (4) OVXe group: injected with NS subcutaneously and then sacrificed 14 weeks after OVX as controls by the end of treatment; (5) PTH group: PTH 40 microg.kg(-1).d(-1) was administered; (6) Alen group: Alen 100 microg.kg(-1).d(-1) was administered; (7) A + P group: PTH 40 microg.kg(-1).d(-1) and Alen 100microg.kg(-1).d(-1) were administered. In groups 4 approximately 7, different medicines were injected subcutaneously QD 5 times per week from the 6th week to the 14th week after OVX and then the rats were killed and their right femurs, lumbar vertebrae, and samples of blood and urine were collected. Absorptometry was used to measure the BMD of the right femur and lumbar vertebrae. The serum calcium, phosphate, creatinine, alanine transaminase, and alkaline phosphatase (ALP) activity were measured by automatic biochemical analysis. The bone resorption marker urine deoxypyridinoline/creatinine (UDpd/Cr) level was measured by enzyme-linked immuosorbent assay. RESULTS: Six weeks after OVX the ALP and UDpd/Cr levels in the OVXb group were 101 U/L +/- 59 U/L and (118 +/- 32) x 10(-6) respectively, both significantly higher than those of the baseline group (58 U/L +/- 10 U/L and (48 +/- 34) x 10(-6) respectively, both P < 0.01) and the BMD results of the OVXb group were all significantly lower than those in the baseline group (all P < 0.01), which indicated that an OVX osteoporotic rat model was established successfully. The ALP and UDpd/Cr levels of the Alen group were 61 U/L +/- 28 U/L and (17 +/- 39) x 10(-6), significantly lower than those of the PTH group 120 U/L +/- 36 U/L and (111 +/- 26) x 10(-6) respectively, both P < 0.01) and the UDpd/Cr levels of the A + P group were between those of the Alen group and those of the PTH group. The BMD levels of the femur and lumbar vertebrae of the PTH, Alen, and A + P groups were all significantly higher than those of the control groups (all P < 0.01), and were similar to or higher than those of the sham operation group without significant differences between the PTH and Alen groups. The BMD level of the lumber vertebrae of the A + P group were significantly higher than those in the PTH group (all P < 0.05), and the femoral BMD results of the A + P group were significantly higher than those in the PTH and Alen groups (all P < 0.01). CONCLUSION: PTH and Alen are all effective on osteoporosis. In particular, the combination of PTH and Alen is more effective on increasing the BMD level.

[Leptin and clustering of the components of risk factors for metabolic syndrome].

OBJECTIVES: To evaluate relationship between serum level of leptin and the components of risk factors for metabolic syndrome and to analyze the characteristics and laws of clustering of the risk factors. METHODS: Totally, 795 non-diabetic adult Chinese subjects (691 men and 104 women, aged 40 - 75 years) from a diabetes prevalence survey in 2000 were involved in this study. Measurements included serum levels of true insulin (TI), leptin, fasting lipids, fasting glucose (FBG) and 2 h postchallenge glucose, as well as seated blood pressure (BP), body mass index (BMI), ratio of waist circumference to hip circumference (WHR), calculated quantitative insulin sensitivity check index (QUICKI), etc. Relationship between serum level of leptin and all the variables mentioned above was studied by statistical methods such as factor analysis, etc. RESULTS: Serum level of leptin in the study subjects increased with the number of components of abnormal metabolism they had. Detection rates of obesity, hypertension, dyslipidemia and metabolic syndrome were significantly higher in those with the upper tertile of serum leptin level than in those with the lower tertile. Factor analysis revealed that variation of the 11 variables including serum level of leptin was affected by the three factors, i.e., the central factor associated with BMI, WHR, FTI, QUICKI and higher serum level of triglyceride (TG) and lower serum level of high-density lipoprotein-cholesterol (HDL-C), the glucose intolerance factor loaded with blood glucose level, FTI, QUICKI and higher serum level of TG (in women only) and the hypertension factor loaded with blood pressure and BMI (in men only), which could explain 62.0% and 66.7% of total variance in men and women, respectively, and higher serum level of TI and insulin resistance also loaded with both the central factor and glucose tolerance factor. CONCLUSIONS: Serum level of leptin was significantly associated with the key markers of metabolic syndrome. Hyperleptinaemia could be a new component of metabolic syndrome. Clustering of the risk factors for metabolic syndrome could be affected by many factors, and although insulin resistance played an important role in it, insulin resistance alone could not explain its etiology.

[Role of leptin in the pathogenesis of obesity-related hypertension].

OBJECTIVE: To assess the role of leptin in the pathogenesis of obesity-related hypertension and the relationship between blood pressure (BP), and body mass index (BMI), insulin resistance and leptin were examined. METHODS: 560 non-diabetic men, aged 35 - 75, selected from volunteers of health screening test during 2 000 were divided into hypertension group (n = 321, BP >or= 140/90 mm Hg without antihypertensive medication). and normal blood pressure group (n = 239). The body weight, waist hip ratio,BP, plasma glucose, serum lipids, true insulin (TI) and leptin were measured after overnight fast. Insulin sensitivity was assessed by the HOMA insulin resistance index (HOMA-R). RESULTS: Fasting leptin level showed good correlation with BMI, fasting TI, HOMA-R, BP and also triglycerides (all P < 0.01). After adjustment for age, BMI and HOMA-R, serum leptin was still positively correlated to SBP (r = 0.11, P < 0.05), and was significantly higher in hypertensive subjects than in normotensive subjects (geometric mean 6.4 vs 4.7 micro g/L, P < 0.001). Logistic regression analysis demonstrated that leptin remained significantly associated with hypertension after adjustment for potentially confounding factors. CONCLUSION: Leptin may play an important role in the pathogenesis of obesity related hypertension.

[The relationship between serum leptin, proinsulin, true insulin levels and insulin resistance in non-diabetic subjects: a population-based study].

OBJECTIVE: Leptin is involved in the regulation of body weight and metabolism. Previous data have suggested that leptin levels are related to insulin resistance and in a few reports with impaired insulin secretion. Some even revealed the existence of adipoinsular axis. However, little is known of these relations in Chinese population. With the availability of measurements of true insulin (TI), proinsulin (PI) and leptin, we examined the possible correlation of leptin with TI, PI and with insulin resistance (the HOMA model) in non-diabetic subjects of north China. We also evaluated whether leptin levels were associated with impaired insulin secretion, as evaluated by the fasting PI/TI ratio. METHODS: 902 non-diabetic subjects (670 with normal and 232 impaired glucose tolerance, aged 30 - 80 y) from a population of Beijing residents who underwent a diabetes survey in 2000 were studied. Fasting serum leptin, PI and TI levels were detected by sensitive and specific enzyme-linked immunosorbent assays (ELISA) which were all developed in our laboratory. RESULTS: Serum leptin values were higher in women. Correlation analysis showed that leptin levels were significantly correlated with fasting TI, PI and insulin resistance (HOMA-IR) (in men, n = 794, r = 0.345, 0.236 and 0.364 respectively; in women, n = 110, r = 0.574, 0.375 and 0.576 respectively, P < 0.001), but not with PI/TI ratio (r = -0.09, P < 0.01) in both sex. After adjustment for age, body mass index (BMI) and waist-to-hip ratio (WHR), leptin levels remained significantly correlated with TI, PI and HOMA-IR, although the magnitude of the association was considerably attenuated. CONCLUSIONS: TI and PI levels were positively related to leptin levels independent of obesity and body fat distribution. Thus, subjects with increased insulin levels and/or insulin resistance may be relatively resistant to the effects of leptin, suggesting a dysfunction of leptin-insulin axis. However, leptin levels are not significantly associated with the fasting PI/TI ratio suggesting that leptin levels are not associated with an impairment in insulin secretion. The role of association between hyperinsulinemia/insulin resistance and hyperleptinemia/leptin resistance in the pathogenesis of insulin resistance-related diseases needs further study.

[Precision of rat BMD measurements by dual-energy X-ray absorptiometry in vitro].

OBJECTIVE: To evaluate the precision of rat bone mineral density (BMD) measurements by Norland Excellplus dual-energy X-ray absorptiometry (DXA) and to investigate the BMD changes in ovariectomized (Ovx) rats in vitro. METHODS: (1) The coefficients of variation (CV) for BMD measurements at various skeletal regions were repeatedly determined by DXA in 10 Wistar rats in vitro. (2) BMD in lumbar vertebra (L5) and both sides of femurs was measured in total 90 rats. And (3) changes in BMD between Ovx and sham rats were compared. RESULTS: (1) The short-term CVs of BMD measurements in different regions by DXA were as follows, 1.58% for lumbar vertebra (L5), 0.90% for left femur, and 0.86% for right femur, respectively. The long-term CVs were 2.22% for lumbar vertebra (L5), 1.09% for left femur, and 1.20% for right femur. (2) The BMD values in 90 Wistar rats were (127.5 +/- 12.3) in lumbar vertebra (L5), (82.6 +/- 11.3) in corpus vertebra (L5'), (150.7 +/- 10.6) in left femur and (149.9 +/- 10.6) mg/cm2 in right femur, respectively. The correlation coefficient of BMD measurements between left and right femurs was 0.792 (P < 0.001). (3) In Ovx group, the BMD values of corpus vertebra (L5') and distal femurs were significantly decreased, that was 10.0%-17.5% lower in comparison with sham group (P < 0.001). CONCLUSIONS: Measurement of rat BMD in vitro by Norland Excellplus DXA is a useful method, and it can reflect the changes in rat bone masses with good precision.