Cadmium inhibits calcium activity in hippocampal CA1 neurons of freely moving mice

Cadmium (Cd) is a ubiquitous toxic heavy metal and a potential neurotoxicant due to its wide use in industrial manufacturing processes and commercial products, including fertilizers. The general population is exposed to Cd through food and smoking due to high transfer rates of Cd from contaminated soil. Cd has been shown to mimic calcium ions (Ca2+) and interfere with intracellular Ca2+ levels and Ca2+ signaling in in vitro studies. However, nothing is known about Cd's effects on Ca2+ activity in neurons in live animals. This study aimed to determine if Cd disrupts Ca2+ transients of neurons in CA1 region of the hippocampus during an associative learning paradigm. We utilized in vivo Ca2+ imaging in awake, freely moving C57BL/6 mice to measure Ca2+ activity in CA1 excitatory neurons expressing genetically encoded Ca2+ sensor GCaMP6 during an associative learning paradigm. We found that a smaller proportion of neurons are activated in Cd-treated groups compared to control during fear conditioning, suggesting that Cd may contribute to learning and memory deficit by reducing activity of neurons. We observed these effects at Cd exposure levels that result in blood Cd levels comparable to the general US population levels. This provides a possible molecular mechanism for Cd interference of learning and memory at exposure levels relevant to US adults. To our knowledge, our study is the first to describe Cd effects on brain Ca2+ activity in vivo in freely behaving mice.

Multiparametric MRI-based radiomics nomogram for predicting malignant transformation of sinonasal inverted papilloma

AIM

To investigate the feasibility of a radiomics nomogram model for predicting malignant transformation in sinonasal inverted papilloma (IP) based on radiomic signature and clinical risk factors.

MATERIALS AND METHODS

This single institutional retrospective review included a total of 143 patients with IP and 75 patients with IP with malignant transformation to squamous cell carcinoma (IP-SCC). All patients underwent surgical pathology and had preoperative magnetic resonance imaging (MRI) and computed tomography (CT) sinus studies between June 2014 and February 2022. Radiomics features were extracted from contrast-enhanced T1-weighted images (CE-T1WI), T2-weighted images (T2WI), and apparent diffusion coefficient (ADC) maps. The least absolute shrinkage and selection operator (LASSO) were performed to select the features extracted from the sequences mentioned above. Independent clinical risk factors were identified by multivariate logistic regression analysis. Radiomics nomogram was constructed by incorporating independent clinical risk factors and radiomics signature. Based on discrimination and calibration, the diagnostic performance of the nomogram was evaluated.

RESULTS

Twelve radiomics features were selected to develop the radiomics model with an area under the curve (AUC) of 0.987 and 0.989, respectively. Epistaxis (p=0.011), T2 equal signal (p=0.003), extranasal invasion (p<0.001), and loss of convoluted cerebriform pattern (p=0.002) were identified as independent clinical predictors. The radiomics nomogram model showed excellent calibration and discrimination (AUC: 0.993, 95% confidence interval [CI]: 0.985-1.00 and 0.990, 95% CI: 0.974-1.00) in the training and validation sets, respectively.

CONCLUSION

The nomogram that the combined radiomics signature and clinical risk factors showed a satisfactory ability to predict IP-SCC.

Factors associated with nocturnal and diurnal glycemic variability in patients with type 2 diabetes: a cross-sectional study

PURPOSE

There is little information on factors that influence the glycemic variability (GV) during the nocturnal and diurnal periods. We aimed to examine the relationship between clinical factors and GV during these two periods.

METHODS

This cross-sectional study included 134 patients with type 2 diabetes. 24-h changes in blood glucose were recorded by a continuous glucose monitoring system. Nocturnal and diurnal GV were assessed by standard deviation of blood glucose (SDBG), coefficient of variation (CV), and mean amplitude of glycemic excursions (MAGE), respectively. Robust regression analyses were performed to identify the factors associated with GV. Restricted cubic splines were used to determine dose-response relationship.

RESULTS

During the nocturnal period, age and glycemic level at 12:00 A.M. were positively associated with GV, whereas alanine aminotransferase was negatively associated with GV. During the diurnal period, homeostatic model assessment 2-insulin sensitivity (HOMA2-S) was positively associated with GV, whereas insulin secretion-sensitivity index-2 (ISSI2) was negatively associated with GV. Additionally, we found a J-shape association between the glycemic level at 12:00 A.M. and MAGE, with 9.0 mmol/L blood glucose level as a cutoff point. Similar nonlinear associations were found between ISSI2 and SDBG, and between ISSI2 and MAGE, with ISSI2 value of 175 as a cutoff point.

CONCLUSION

Factors associated with GV were different between nocturnal and diurnal periods. The cutoff points we found in this study may provide the therapeutic targets for beta-cell function and pre-sleep glycemic level in clinical practice.

Inducible and Conditional Activation of Adult Neurogenesis Rescues Cadmium-Induced Hippocampus-Dependent Memory Deficits in ApoE4-KI Mice

The apolipoprotein E (ApoE) gene is a genetic risk factor for late-onset Alzheimer's disease, in which ε4 allele carriers have increased risk compared to the common ε3 carriers. Cadmium (Cd) is a toxic heavy metal and a potential neurotoxicant. We previously reported a gene-environment interaction (GxE) effect between ApoE4 and Cd that accelerates or increases the severity of the cognitive decline in ApoE4-knockin (ApoE4-KI) mice exposed to 0.6 mg/L CdCl2 through drinking water compared to control ApoE3-KI mice. However, the mechanisms underlying this GxE effect are not yet defined. Because Cd impairs adult neurogenesis, we investigated whether genetic and conditional stimulation of adult neurogenesis can functionally rescue Cd-induced cognitive impairment in ApoE4-KI mice. We crossed either ApoE4-KI or ApoE3-KI to an inducible Cre mouse strain, Nestin-CreERTM:caMEK5-eGFPloxP/loxP (designated as caMEK5), to generate ApoE4-KI:caMEK5 and ApoE3-KI:caMEK5. Tamoxifen administration in these mice genetically and conditionally induces the expression of caMEK5 in adult neural stem/progenitor cells, enabling the stimulation of adult neurogenesis in the brain. Male ApoE4-KI:caMEK5 and ApoE3-KI:caMEK5 mice were exposed to 0.6 mg/L CdCl2 throughout the experiment, and tamoxifen was administered once Cd-induced impairment in spatial working memory was consistently observed. Cd exposure impaired spatial working memory earlier in ApoE4-KI:caMEK5 than in ApoE3-KI:caMEK5 mice. In both strains, these deficits were rescued after tamoxifen treatment. Consistent with these behavioral findings, tamoxifen treatment enhanced adult neurogenesis by increasing the morphological complexity of adult-born immature neurons. These results provide evidence for a direct link between impaired spatial memory and adult neurogenesis in this GxE model.

Effect of Chronic Cadmium Exposure on Brain and Liver Transporters and Drug-Metabolizing Enzymes in Male and Female Mice Genetically Predisposed to Alzheimer's Disease

Cadmium (Cd) exposure is associated with increased Alzheimer's disease (AD) risks. The human Apolipoprotein E (ApoE) gene encodes a lipid-transporting protein that is critical for brain functions. Compared with ApoE2 and E3, ApoE4 is associated with increased AD risk. Xenobiotic biotransformation-related genes have been implicated in the pathogenesis of AD. However, little is known about the effects of Cd, ApoE, and sex on drug-processing genes. We investigated the Cd-ApoE interaction on the transcriptomic changes in the brains and livers of ApoE3/ApoE4 transgenic mice. Cd disrupts the transcriptomes of transporter and drug-processing genes in brain and liver in a sex- and ApoE-genotype-specific manner. Proinflammation related genes were enriched in livers of Cd-exposed ApoE4 males, whereas circadian rhythm and lipid metabolism related genes were enriched in livers of Cd-exposed ApoE3 females. In brains, Cd up-regulated the arachidonic acid-metabolizing Cyp2j isoforms only in the brains of ApoE3 mice, whereas the dysregulation of cation transporters was male-specific. In livers, several direct target genes of the major xenobiotic-sensing nuclear receptor pregnane X receptor were uniquely upregulated in Cd-exposed ApoE4 males. There was a female-specific hepatic upregulation of the steroid hormone-metabolizing Cyp2 isoforms and the bile acid synthetic enzyme Cyp7a1 by Cd exposure. The dysregulated liver transporters were mostly involved in intermediary metabolism, with the most significant response observed in ApoE3 females. In conclusion, Cd dysregulated the brain and liver drug-processing genes in a sex- and ApoE-genotype specific manner, and this may serve as a contributing factor for the variance in the susceptibility to Cd neurotoxicity. SIGNIFICANCE STATEMENT: Xenobiotic biotransformation plays an important role in modulating the toxicity of environmental pollutants. The human ApoE4 allele is the strongest genetic risk factor for AD, and cadmium (Cd) is increasingly recognized as an environmental factor of AD. Very little is known regarding the interactions between Cd exposure, sex, and the genes involved in xenobiotic biotransformation in brain and liver. The present study has addressed this critical knowledge gap.

[Analysis of changes in self-efficacy and its influencing factors in type 2 diabetic patients after community-based self-management group intervention]

Objective: To analyze the changes in self-efficacy and its influencing factors in type 2 diabetic patients after community-based self-management group intervention. Methods: From August to November 2014, a 3-month community-based self-management intervention study of type 2 diabetes patients was implemented in Fangshan District, Beijing. 510 patients were recruited through posters, household inquiries and telephone notification and then were randomly divided into intervention group (260 patients) and control group (250 patients). Finally, 500 patients completed the study, including 259 in the intervention group and 241 in the control group. Self-efficacy score was measured through face-to-face interview at different time points, including pre-intervention, post-intervention, 2 years after the intervention and 5 years after the intervention, respectively. A two-level random coefficient model was fitted to analyze the long-term trend of self-efficacy and its relationship with group intervention. Results: Individual-level educational attainment, disease duration as well as their treatment plans had a positive correlation with self-efficacy of type 2 diabetic patients while gender and age did not affect their self-efficacy. Patients with junior middle school education, senior high school education and university and above education had 4.66 (P<0.05), 6.40 (P<0.05) and 11.02 (P<0.05) points higher than those with primary education, respectively. The self-efficacy of diabetic patients increased by 0.23 (P<0.05) for each additional course year. The effect of treatment plan on self-efficacy was mainly reflected in the self-efficacy of taking medication or insulin injection as prescribed and blood glucose monitoring. After controlling for the confounding factors, i.e., gender, age, disease duration, educational attainment, and treatment plan, self-efficacy scores at the post-intervention increased in both groups compared to those at the pre-intervention. The intervention group had 7.95 points higher than the control group (P<0.05). After the intervention, the self-efficacy scores of both groups decreased year by year while the intervention group declined faster, with 5.41 points (P<0.05) at 2 years after the intervention and 8.94 points (P<0.05) at 5 years after the intervention. Conclusion: Community-based self-management group intervention could improve the self-efficacy of type 2 diabetic patients while the self-efficacy decreases year by year in the absence of follow-up intervention.

Adolescent cadmium exposure impairs cognition and hippocampal neurogenesis in C57BL/6 mice

Cadmium (Cd) is a toxic heavy metal and a significant public health concern. Epidemiological studies suggest that Cd is a potential neurotoxicant, and its exposure is associated with cognitive deficits in children, adults, and seniors. Our previous study has found that adulthood-only Cd exposure can impair cognition in mice. However, few studies have addressed the effects of Cd exposure during adolescence on cognitive behavior in animals later in life. In the present study, we exposed 4-week-old male C57BL/6 mice to 3 mg/L Cd via drinking water for 28 weeks and assessed their hippocampus-dependent learning and memory. Cd did not affect anxiety or locomotor activity in the open field test. However, Cd exposure impaired short-term spatial memory and contextual fear memory in mice. A separate cohort of 4-week-old mice was similarly exposed to Cd for 13 weeks to investigate the potential mechanism of Cd neurotoxicity on cognition. We observed that Cd-treated mice had fewer adult-born cells, adult-born neurons, and a reduced proportion of adult-born cells that differentiated into mature neurons in the subgranular zone of the dentate gyrus. These results suggest that Cd exposure from adolescence to adulthood is sufficient to cause cognitive deficits and impair key processes of hippocampal neurogenesis in mice.

Cadmium exposure modulates the gut-liver axis in an Alzheimer's disease mouse model

The human Apolipoprotein E4 (ApoE4) variant is the strongest known genetic risk factor for Alzheimer's disease (AD). Cadmium (Cd) has been shown to impair learning and memory at a greater extent in humanized ApoE4 knock-in (ApoE4-KI) mice as compared to ApoE3 (common allele)-KI mice. Here, we determined how cadmium interacts with ApoE4 gene variants to modify the gut-liver axis. Large intestinal content bacterial 16S rDNA sequencing, serum lipid metabolomics, and hepatic transcriptomics were analyzed in ApoE3- and ApoE4-KI mice orally exposed to vehicle, a low dose, or a high dose of Cd in drinking water. ApoE4-KI males had the most prominent changes in their gut microbiota, as well as a predicted down-regulation of many essential microbial pathways involved in nutrient and energy homeostasis. In the host liver, cadmium-exposed ApoE4-KI males had the most differentially regulated pathways; specifically, there was enrichment in several pathways involved in platelet activation and drug metabolism. In conclusion, Cd exposure profoundly modified the gut-liver axis in the most susceptible mouse strain to neurological damage namely the ApoE4-KI males, evidenced by an increase in microbial AD biomarkers, reduction in energy supply-related pathways in gut and blood, and an increase in hepatic pathways involved in inflammation and xenobiotic biotransformation.

Incidence and risk factors of female urinary incontinence: a 4-year longitudinal study among 24 985 adult women in China

OBJECTIVE

To estimate the incidence of urinary incontinence (UI), including its subtypes stress UI (SUI), urgency UI (UUI) and mixed UI (MUI), and to examine risk factors for de novo SUI and UUI in Chinese women.

DESIGN

Nationwide longitudinal study.

SETTING

Six geographic regions of China.

PARTICIPANTS

Women aged ≥20 years old were included using a multistage, stratified, cluster sampling method.

METHODS

This study was conducted between May 2014 and March 2016, with follow up in 2018. Data on demographics, medical history, lifestyle and physiological and anthropometric information were collected.

MAIN OUTCOME MEASUREMENTS

Incidence, rate ratio (RR).

RESULTS

Analyses included 24 985 women (mean age 41.9 years).The follow-up response rate was 55.5%, median follow-up time was 3.7 years. The standardised incidences of UI, SUI, UUI and MUI were 21.2, 13.1, 3.0 and 5.1 per 1000 person-years, respectively. Risk factors for de novo SUI included delivery pattern (vaginal spontaneous delivery RR 2.12, 95% CI 1.62-2.78 and instrumental delivery RR 3.30, 95% CI 1.99-5.45), high body mass index (BMI) (overweight RR 1.52, 95% CI 1.33-1.74 and obesity RR 1.67, 95% CI 1.32-2.11), cigarette smoking (RR 1.54, 95% CI 1.12-2.12), chronic cough (RR 1.44, 95% CI 1.17-1.76), diabetes (RR 1.33, 95% CI 1.10-1.60) and older age (50-59 years RR 1.49, 95% CI 1.16-1.90 and 60-69 years RR 1.61, 95% CI 1.22-2.13).The risk factors significantly associated with de novo UUI were age (RR increased from 1.21, 95% CI 0.74-1.99, at 30-39 years to 6.3, 95% CI 3.85-10.30, at >70 years) and diabetes (RR 1.48, 95% CI 1.05-2.09).

CONCLUSIONS

The incidence of female UI is 21.2 per 1000 person-years in China. Delivery (vaginal spontaneous delivery, instrumental delivery), high BMI, cigarette smoking, chronic cough, diabetes and older age were risk factors.

TWEETABLE ABSTRACT

The incidence of female urinary incontinence was 21.2 per 1000 person-years in China. Delivery, BMI, diabetes and old age are risk factors.

[Evaluation on the quality of 236 National Demonstration Areas for comprehensive prevention and control of chronic diseases betweem 2017 and 2019]

Objective: To evaluate the quality of the National Demonstration Area for Comprehensive Prevention and Control of NCDs (referred to as "the Demonstration Area"). Methods: Based on the evaluation scores of the Demonstration Area field survey from 2017 to 2019, we counted the scores of each indicator, comparing the scores among indicators and regions. x±s was used to describe the scores. The 95%CI of the score was used to test the statistical difference among regions. Each score was converted into a hundred-mark system to compare the scores among indicators. Results: Of 236 Demonstration Areas, the total score was 83.5. The scores of the first-level indicator listed from high to low appeared as Integrating System of NCD Prevention and Control (92.8), Policy Perfection (90.3), Building Supportive Environment for NCD Prevention and Control (88.4), Implementation of Health Education and Health Promotion (87.4), Whole-course Management of NCDs (78.1), Innovation and Guidance (76.5), Surveillance and Evaluation (75.1). Total scores were higher in the east (259.2±18.8) comparing to the middle (243.2±15.2) or the west (245.4±19.7) regions. Conclusions: Substantial variations on the quality in the Demonstration Area existed across different regions in China. These disparities are important to the government when developing health policies and allocating resources. Whole-course Management of NCDs, Surveillance and Evaluation, and Innovation and Guidance in the Demonstration Area also needs to be improved.

Imaging orbital ferromagnetism in a moiré Chern insulator

Electrons in moiré flat band systems can spontaneously break time-reversal symmetry, giving rise to a quantized anomalous Hall effect. In this study, we use a superconducting quantum interference device to image stray magnetic fields in twisted bilayer graphene aligned to hexagonal boron nitride. We find a magnetization of several Bohr magnetons per charge carrier, demonstrating that the magnetism is primarily orbital in nature. Our measurements reveal a large change in the magnetization as the chemical potential is swept across the quantum anomalous Hall gap, consistent with the expected contribution of chiral edge states to the magnetization of an orbital Chern insulator. Mapping the spatial evolution of field-driven magnetic reversal, we find a series of reproducible micrometer-scale domains pinned to structural disorder.

The Effects of Gene-Environment Interactions Between Cadmium Exposure and Apolipoprotein E4 on Memory in a Mouse Model of Alzheimer's Disease

Cadmium (Cd) is a heavy metal of great public health concern. Recent studies suggested a link between Cd exposure and cognitive decline in humans. The ε4 allele, compared with the common ε3 allele, of the human apolipoprotein E gene (ApoE) is associated with accelerated cognitive decline and increased risks for Alzheimer's disease (AD). To investigate the gene-environment interactions (GxE) between ApoE-ε4 and Cd exposure on cognition, we used a mouse model of AD that expresses human ApoE-ε3 (ApoE3-KI [knock-in]) or ApoE-ε4 (ApoE4-KI). Mice were exposed to 0.6 mg/l CdCl2 through drinking water for 14 weeks and assessed for hippocampus-dependent memory. A separate cohort was sacrificed immediately after exposure and used for Cd measurements and immunostaining. The peak blood Cd was 0.3-0.4 µg/l, within levels found in the U.S. general population. All Cd-treated animals exhibited spatial working memory deficits in the novel object location test. This deficit manifested earlier in ApoE4-KI mice than in ApoE3-KI within the same sex and earlier in males than females within the same genotype. ApoE4-KI but not ApoE3-KI mice exhibited reduced spontaneous alternation later in life in the T-maze test. Finally, Cd exposure impaired neuronal differentiation of adult-born neurons in the hippocampus of male ApoE4-KI mice. These data suggest that a GxE between ApoE4 and Cd exposure leads to accelerated cognitive impairment and that impaired adult hippocampal neurogenesis may be one of the underlying mechanisms. Furthermore, male mice were more susceptible than female mice to this GxE effect when animals were young.

A nationwide population-based survey on the prevalence and risk factors of symptomatic pelvic organ prolapse in adult women in China - a pelvic organ prolapse quantification system-based study

Objective

To determine the prevalence, risk factors and burden of symptomatic pelvic organ prolapse (POP) in adult Chinese women.

Design

A nationwide cross‐sectional study.

Setting

Six geographic regions of mainland China.

Participants

Women aged ≥20 years old were included using a multistage, stratified, cluster sampling method from February 2014 through March 2016.

Methods

We conducted a nationwide epidemiological survey. ‘Symptomatic POP’ was determined by a screening questionnaire and physical examination.

Main outcome measurements

Prevalence, odds ratio (OR).

Results

A total of 55 477 women (response rate, 92.5%; mean age, 45.1 years old) were included. The prevalence of symptomatic POP was 9.6% (95% CI 9.3–9.8%) and it increased with age in each stage (P < 0.05). Symptomatic POP‐Q stage II, which mainly involved anterior compartment prolapse, was the most common (7.52%). Minor/moderate burden of symptomatic POP was the most common, with a prevalence of 9.7% (95% CI 9.5–10.0%). The odds for each type of symptomatic POP increased with age (>50 vs 20‐29 years old in symptomatic POP‐Q stage II or higher, OR increased from 1.34 [95% CI 1.32–1.45] to 7.34 [95% CI 4.34–12.41]) and multiple vaginal deliveries (multiparous [≥3] vs nulliparous in symptomatic POP‐Q stage II or higher, OR increased from 1.91 [1.71–2.13] to 2.78 [2.13–3.64]).

Conclusions

We found a lower prevalence of symptomatic POP than that found in other surveys. The main type of symptomatic POP was anterior compartment prolapse, indicating that it should be considered first. Older age and multiple vaginal deliveries increased the odds of each type of symptomatic POP.

Tweetable abstract

The prevalence of female symptomatic pelvic organ prolapse (POP) was 9.6% in China. It is related to old age and multiple vaginal deliveries.

The prevalence of female symptomatic pelvic organ prolapse (POP) was 9.6% in China. It is related to old age and multiple vaginal deliveries.

Synovial mesenchymal stem cells effectively alleviate osteoarthritis through promoting the proliferation and differentiation of meniscus chondrocytes

OBJECTIVE

To investigate the relationship between the meniscal defect area and OA progression and explore the effect and mechanism of SMSCs cell therapy in knee osteoarthritis (OA) rat model.

MATERIALS AND METHODS

For animal experiments, knee osteoarthritis (OA) model was constructed in Sprague Dawley (SD) rats by removing the medial meniscus of the right knee. Synovial mesenchymal stem cells (SMSCs) were engrafted by injecting into the right knee cavity. For in vitro experiments, CCK-8 assay was performed to evaluate the proliferation and differentiation of BMSCs and ATDC5 cells after co-cultured with SMSCs. qRT-PCR analysis was performed to detect the expressions of chondrogenic genes in BMSCs and ATDC5 cells after co-cultured with SMSCs. Western blot analysis was conducted to detect the phosphorylations of c-Jun N-terminal kinase (JNK) and extracellular regulated protein kinases (ERK) in MAPK signaling of BMSCs and ATDC5 cells. Enzyme-linked immunosorbent assay (ELISA) was performed to detect the serum levels of interleukin (IL)-1β, IL-1β, IL-6, IL-18 and C-reactive protein (CRP).

RESULTS

Results showed that meniscus damaged area is positively correlated to serum inflammatory factor levels. In vitro study showed that the proliferation and differentiation of BMSCs and ATDC5 cells were promoted after co-cultured with SMSCs. By co-culturing with SMSCs, the MAPK signaling pathway was activated and the expression of chondrogenic markers such as aggrecan (acan), SRY-related high mobility group-box gene 9 (sox9) and Type II collagen a1 (col2a1), was up-regulated both in BMSCs and ATDC5 cells. In vivo study showed SMSCs cell therapy significantly decreased serum inflammatory factor levels and protected cartilage by upregulating the expression of chondrogenic genes of meniscus chondrocytes derived from OA rats.

CONCLUSIONS

For the first time, we found the positive correlation between meniscal defect area and OA progression and demonstrated the effect and mechanism of SMSCs cell therapy in knee osteoarthritis (OA) treatment.

Inducible and Conditional Stimulation of Adult Hippocampal Neurogenesis Rescues Cadmium-Induced Impairments of Adult Hippocampal Neurogenesis and Hippocampus-Dependent Memory in Mice

Cadmium (Cd) is a heavy metal and an environmental pollutant. However, the full spectrum of its neurotoxicity and the underlying mechanisms are not completely understood. Our previous studies demonstrated that Cd exposure impairs adult hippocampal neurogenesis and hippocampus-dependent memory in mice. This study aims to determine if these adverse effects of Cd exposure can be mitigated by genetically and conditionally enhancing adult neurogenesis. To address this issue, we utilized the transgenic constitutive active MEK5 (caMEK5) mouse strain we previously developed and characterized. This mouse strain enables us to genetically and conditionally activate adult neurogenesis by administering tamoxifen to induce expression of a caMEK5 in adult neural stem/progenitor cells, which stimulates adult neurogenesis through activation of the endogenous extracellular signal-regulated kinase 5 mitogen-activated protein kinase pathway. The caMEK5 mice were exposed to 0.6 mg/l Cd through drinking water for 38 weeks. Once impairment of memory was confirmed, tamoxifen was administered to induce caMEK5 expression and to activate adult neurogenesis. Behavior tests were conducted at various time points to monitor hippocampus-dependent memory. Upon completion of the behavior tests, brain tissues were collected for cellular studies of adult hippocampal neurogenesis. We report here that Cd impaired hippocampus-dependent spatial memory and contextual fear memory in mice. These deficits were rescued by the tamoxifen induction of caMEK5 expression. Furthermore, Cd inhibition of adult hippocampal neurogenesis was also reversed. This rescue experiment provides strong evidence for a direct link between Cd-induced impairments of adult hippocampal neurogenesis and hippocampus-dependent memory.

Cadmium Exposure Impairs Adult Hippocampal Neurogenesis

Cadmium (Cd) is an environmental pollutant of considerable interest throughout the world and potentially a neurotoxicant. Our recent data indicate that Cd exposure induces impairment of hippocampus-dependent learning and memory in mice. However, the underlying mechanisms for this defect are not known. The goal of this study was to determine if Cd inhibits adult neurogenesis and to identify underlying signaling pathways responsible for this impairment. Adult hippocampal neurogenesis is a process in which adult neural progenitor/stem cells (aNPCs) in the subgranular zone (SGZ) of the dentate gyrus (DG) generate functional new neurons in the hippocampus which contributes to hippocampus-dependent learning and memory. However, studies concerning the effects of neurotoxicants on adult hippocampal neurogenesis and the underlying signaling mechanisms are limited. Here, we report that Cd significantly induces apoptosis, inhibits proliferation, and impairs neuronal differentiation in primary cultured aNPCs derived from the SGZ. In addition, the c-jun NH2-terminal kinase (JNK) and p38 mitogen-activated protein (MAP) kinase signaling pathways are activated by Cd and contribute to its toxicity. Furthermore, we exposed 8-week-old male C57BL/6 mice to Cd through drinking water for 13 weeks to assess the effects of Cd on adult hippocampal neurogenesis in vivo. Cd treatment reduced the number of 5-week old adult-born cells in the DG and impaired the differentiation of adult-born hippocampal neurons. These results suggest that Cd exposure impairs adult hippocampal neurogenesis both in vitro and in vivo. This may contribute to Cd-mediated inhibition of hippocampus-dependent learning and memory.

Dynamics of a hippocampal neuronal ensemble encoding trace fear memory revealed by in vivo Ca2+ imaging

Although the biochemical signaling events in area CA1 of the hippocampus underlying memory acquisition, consolidation, retrieval, and extinction have been extensively studied, little is known about the activity dynamics of hippocampal neurons in CA1 during Pavlovian fear conditioning. Here, we use fiber-optic confocal microscopy coupled with the calcium indicator GCaMP6m to monitor neuron activity in freely moving mice during trace fear conditioning. We show that the activity of a group of CA1 neurons increases not only after the stimulus presentations, but also during the stimulus-free trace period when the conditioned mice exhibit a high level of freezing behavior. Therefore, we designate these cells “trace cells”. Interestingly, the activity of the trace cells increases in response to the conditioned stimuli during memory retrieval but diminishes during memory extinction. Importantly, the dynamics of neuron activity exhibit a high degree of correlation with the freezing behavior of the mice, suggesting that a neuronal ensemble responsible for encoding the trace fear memory is repeatedly reactivated during memory retrieval and later extinguished during memory extinction.

Cadmium Exposure Impairs Cognition and Olfactory Memory in Male C57BL/6 Mice

Cadmium (Cd) is a heavy metal of high interest to the superfund initiative. Recent epidemiology studies have suggested a possible association between Cd exposure and cognitive as well as olfactory impairments in humans. However, studies in animal models are needed to establish a direct causal relationship between Cd exposure and impairments in cognition and olfaction. This study aims to investigate the toxic effect of Cd on cognition and olfactory function in mice. One group of 8-week-old C57BL/6 male mice was exposed to 3 mg/l Cd (in the form of CdCl2) through drinking water for 20 weeks for behavior tests and final blood Cd concentration analysis. The behavior tests were conducted before, during, and after Cd exposure to analyze the effects of Cd on cognition and olfactory function. Upon completion of behavior tests, blood was collected to measure final blood Cd concentration. Two additional groups of mice were similarly exposed to Cd for 5 or 13 weeks for peak blood Cd concentration measurement. The peak blood Cd concentration was 2.125-2.25 μg/l whereas the final blood Cd concentration was 0.18 μg/l. At this exposure level, Cd impaired hippocampus-dependent learning and memory in novel object location test, T-maze test, and contextual fear memory test. It also caused deficits in short-term olfactory memory and odor-cued olfactory learning and memory. Results in this study demonstrate a direct relationship between Cd exposure and cognitive as well as olfactory impairments in an animal model.

Effects of oat protein supplementation on skeletal muscle damage, inflammation and performance recovery following downhill running in untrained collegiate men

The positive influence of animal-based protein supplementation during muscle-damaging exercise has been widely studied. However, the effects of plant-based proteins remain unclear and require further clarification. This study investigated the protective role of oat protein against exercise induced muscle damage (EIMD), subsequent inflammation, and loss of performance induced by downhill running. Subjects consumed either oat protein (25 g protein) or a placebo for 14 days prior to a downhill running test and then for 4 days thereafter. Treatments with oat protein for 19 days markedly alleviated eccentric exercise induced skeletal muscle soreness, and reduced the elevation of plasma IL-6 concentrations and serum creatine kinase, myoglobin and C reactive protein contents. In addition, oat protein supplementation significantly inhibited limb edema following damaging exercise, and the adverse effects on muscle strength, knee-joint range of motion, and vertical jump performance were lessened. Furthermore, the administration of oat protein facilitated recovery from exhaustive downhill running in this study. These findings demonstrated that oat protein supplementation has the potential to alleviate the negative effects of eccentric exercise in untrained young males.

An epidemiologic study of pelvic organ prolapse in postmenopausal women: a population-based sample in China

OBJECTIVE

This study aimed to assess the prevalence and factors associated with symptomatic pelvic organ prolapse (POP) in a representative sample of postmenopausal Chinese women.

METHODS

A total of 20,008 postmenopausal Chinese women were recruited to this cross-sectional study between February 2014 and March 2016. The prevalence of symptomatic POP, defined as any stage II or higher POP resulting in symptoms, was assessed using questionnaires and physical examinations. Multivariable logistic regression was used to assess factors associated with symptomatic POP.

RESULTS

Among all women with natural menopause included in the study (mean age =61.98 ± 10.62 years), 2962 of 20,008 women (14.80%, 95% confidence interval [CI] 14.3-15.3%) had symptomatic POP. In the multivariate analysis, women were more likely to have symptomatic POP if aged 50-59 years (adjusted odds ratio [AOR] 1.322, 95% CI 1.123-1.560), 60-69 years (AOR 1.603, 95% CI 1.352-1.907), or above 70 years (AOR 1.824, 95% CI 1.158-2.197), compared with women aged 40-49 years. Having delivered two times (AOR 1.145, 95% CI 1.105-1.292) or three or more times (AOR 1.384, 95% CI 1.214-1.578) was significantly associated with symptomatic POP. Compared with normal weight women, overweight women (AOR 1.365, 95% CI 1.247-1.494) and obese women (AOR 1.548, 95% CI 1.344-1.780) were more likely to have POP. Living in an urban area, smoking, alcohol consumption, cough, constipation, mental labor, physical disease, and gynecological diseases were also associated with symptomatic POP.

CONCLUSIONS

Symptomatic POP affects nearly 15% of postmenopausal women in China. The prevalence of symptomatic POP increases significantly with age, body mass index, and parity.

Diagnostic guidelines for the histological particle algorithm in the periprosthetic neo-synovial tissue

BACKGROUND

The identification of implant wear particles and non-implant related particles and the characterization of the inflammatory responses in the periprosthetic neo-synovial membrane, bone, and the synovial-like interface membrane (SLIM) play an important role for the evaluation of clinical outcome, correlation with radiological and implant retrieval studies, and understanding of the biological pathways contributing to implant failures in joint arthroplasty. The purpose of this study is to present a comprehensive histological particle algorithm (HPA) as a practical guide to particle identification at routine light microscopy examination.

METHODS

The cases used for particle analysis were selected retrospectively from the archives of two institutions and were representative of the implant wear and non-implant related particle spectrum. All particle categories were described according to their size, shape, colour and properties observed at light microscopy, under polarized light, and after histochemical stains when necessary. A unified range of particle size, defined as a measure of length only, is proposed for the wear particles with five classes for polyethylene (PE) particles and four classes for conventional and corrosion metallic particles and ceramic particles.

RESULTS

All implant wear and non-implant related particles were described and illustrated in detail by category. A particle scoring system for the periprosthetic tissue/SLIM is proposed as follows: 1) Wear particle identification at light microscopy with a two-step analysis at low (× 25, × 40, and × 100) and high magnification (× 200 and × 400); 2) Identification of the predominant wear particle type with size determination; 3) The presence of non-implant related endogenous and/or foreign particles. A guide for a comprehensive pathology report is also provided with sections for macroscopic and microscopic description, and diagnosis.

CONCLUSIONS

The HPA should be considered a standard for the histological analysis of periprosthetic neo-synovial membrane, bone, and SLIM. It provides a basic, standardized tool for the identification of implant wear and non-implant related particles at routine light microscopy examination and aims at reducing intra-observer and inter-observer variability to provide a common platform for multicentric implant retrieval/radiological/histological studies and valuable data for the risk assessment of implant performance for regional and national implant registries and government agencies.

Mild Hypothermia Protects Renal Function in Ischemia-reperfusion Kidney: An Experimental Study in Mice

Mild hypothermia reduces the damage caused by hypoxia and oxidative stress, but how this happens is not very clear. Mice were anesthetized and their core body temperature was maintained at 38 ± 0.5°C and 32 ± 0.5°C. The renal artery and renal veins were blocked for 35 minutes and reperfusion was performed. Twenty-four hours later, serum was obtained to detect the concentrations of creatinine. The expression of CIRP, TRX, Bcl-2, and Bax were detected in tissue samples using Western blot. Apoptosis was measured using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling and the apoptosis rates were calculated. SOD and MDA were detected to determine the extent of oxidative damage in different groups. The concentration of creatinine in the NC group was 2.11 ± 0.39 mg/dL. Compared to the IR group, the concentration of creatinine decreased in MH+IR group and showed a significant statistical difference (8.74 ± 1.38 mg/dL vs 15.36 ± 2.13 mg/dL, P < .01); the apoptosis rate also decreased with statistical significance (15.02 ± 1.45% vs 37.02 ± 5.70%, P < .01). Compared to the IR group, the expression of CIRP, TRX, and the Bcl-2/Bax ratio significantly increased in the MH+IR group. The SOD activity in the MH+IR group increased (26.90 ± 4.41 U/mgprot vs 16.85 ± 2.41 U/mgprot, P < .05) and the MDA level decreased (0.76 ± 0.18 nmol/mgprot vs 1.37 ± 0.32 nmol/mgprot, P < .05) compared to those of the IR group. Mild hypothermia protects mice kidneys from ischemia-reperfusion damage by reducing oxidative stress injury and apoptosis.

Myocardial ischaemia reperfusion injury: the challenge of translating ischaemic and anaesthetic protection from animal models to humans

Myocardial ischaemia reperfusion injury is the leading cause of death in patients with cardiovascular disease. Interventions such as ischaemic pre and postconditioning protect against myocardial ischaemia reperfusion injury. Certain anaesthesia drugs and opioids can produce the same effects, which led to an initial flurry of excitement given the extensive use of these drugs in surgery. The underlying mechanisms have since been extensively studied in experimental animal models but attempts to translate these findings to clinical settings have resulted in contradictory results. There are a number of reasons for this such as dose response, the intensity of the ischaemic stimulus applied, the duration of ischaemia and lost or diminished cardioprotection in common co-morbidities such as diabetes and senescence. This review focuses on current knowledge regarding myocardial ischaemia reperfusion injury and cardioprotective interventions both in experimental animal studies and in clinical trials.

A potential strategy for counteracting age-related sarcopenia: preliminary evidence of combined exercise training and leucine supplementation

Previous research has demonstrated the positive effects of concurrent/combined aerobic and resistance exercise or leucine supplementation on skeletal muscle protein synthesis (MPS) and hypertrophy in aging organisms. However, the effects of a multimodal intervention which combines both aerobic and resistance exercise and leucine supplementation has not been fully elucidated. Eighteen month old and 2 month old C57BL/6 mice were assigned to aging control (AC, n = 8), aging and multimodal intervention (AMI, n = 8) and young control (YC, n = 8). Mice in the YC and AC groups were fed an alanine-rich diet (3.4%), and mice in the AMI group received an isonitrogenous leucine-supplemented (5%) diet in combination with combined aerobic (30 minutes swimming) and resistance exercise training (incremental jumping submersed in water with overload corresponding to 40%-50% body weight) for a total of 4 weeks. The gastrocnemius muscles were dissected for western blotting detection (signaling proteins involved in MPS) and the ex vivo determination of protein synthesis and protein content. The muscle strength of the hind limbs was measured pre-experiment and repeated once per week on Sunday for 4 weeks. Mice in the AC and AMI groups showed lower ex vivo protein synthesis, protein content, expression of signaling proteins involved in MPS, maximal grip strength but higher plasma cortisol compared with the YC group post intervention. When compared to AC mice, the multimodal treatment led to lower activity of Sestrin2, higher expression of PI3K III and the phosphorylation of mTOR, p70S6K and 4E-BP1, as well as higher plasma leucine, wet gastrocnemius muscle weight and muscle weight to body weight ratio. Furthermore, the multimodal intervention induced more pronounced anabolic response such as higher ex vivo protein synthesis rate, total protein content, and myofibrillar fractions in gastrocnemius muscle, and greater maximum grip strength. The present research shows that a multimodal intervention including combined both aerobic and resistance exercise training and 5% leucine supplementation has the potential to maintain skeletal muscle protein synthesis and attenuate losses in muscular strength during the aging process.

Lead exposure in late adolescence through adulthood impairs short-term spatial memory and the neuronal differentiation of adult-born cells in C57BL/6 male mice

Lead is a neurotoxicant of immense public health importance. Epidemiology studies suggest that heavy metal exposure may be associated with an increased risk of cognitive decline, yet few studies to date have assessed the effect of adult lead exposure on cognitive behavior in animal models. Here, we exposed 6-week-old male C57BL/6 mice to 0.2% lead acetate via drinking water for 12 weeks starting at 6 weeks of age and then assessed for deficits in hippocampus-dependent spatial memory and impairment of adult hippocampal neurogenesis. Lead did not cause locomotor deficits or anxiety in the open field test. However, we found that adult, subchronic lead exposure was sufficient to cause deficits in spatial short-term memory and these deficits persisted through at least 2 months post-lead exposure. Furthermore, we observed that lead-treated mice had fewer adult-born, mature neurons in the dentate gyrus of the hippocampus compared to control animals, suggesting that lead exposure during adolescence and adulthood may impair the neuronal differentiation of adult-born cells. These data suggest that adult lead exposure is sufficient to cause persistent deficits in spatial short-term memory and impair key processes in adult hippocampal neurogenesis.

Conditional deletion of Ndufs4 in dopaminergic neurons promotes Parkinson's disease-like non-motor symptoms without loss of dopamine neurons

Reduction of mitochondrial complex I activity is one of the major hypotheses for dopaminergic neuron death in Parkinson’s disease. However, reduction of complex I activity in all cells or selectively in dopaminergic neurons via conditional deletion of the Ndufs4 gene, a subunit of the mitochondrial complex I, does not cause dopaminergic neuron death or motor impairment. Here, we investigated the effect of reduced complex I activity on non-motor symptoms associated with Parkinson’s disease using conditional knockout (cKO) mice in which Ndufs4 was selectively deleted in dopaminergic neurons (Ndufs4 cKO). This conditional deletion of Ndufs4, which reduces complex I activity in dopamine neurons, did not cause a significant loss of dopaminergic neurons in substantia nigra pars compacta (SNpc), and there was no loss of dopaminergic neurites in striatum or amygdala. However, Ndufs4 cKO mice had a reduced amount of dopamine in the brain compared to control mice. Furthermore, even though motor behavior were not affected, Ndufs4 cKO mice showed non-motor symptoms experienced by many Parkinson’s disease patients including impaired cognitive function and increased anxiety-like behavior. These data suggest that mitochondrial complex I dysfunction in dopaminergic neurons promotes non-motor symptoms of Parkinson’s disease and reduces dopamine content in the absence of dopamine neuron loss.

Gene-environment interaction between lead and Apolipoprotein E4 causes cognitive behavior deficits in mice

Background

Alzheimer’s disease (AD) is characterized by progressive cognitive decline and memory loss. Environmental factors and gene-environment interactions (GXE) may increase AD risk, accelerate cognitive decline, and impair learning and memory. However, there is currently little direct evidence supporting this hypothesis.

Methods

In this study, we assessed for a GXE between lead and ApoE4 on cognitive behavior using transgenic knock-in (KI) mice that express the human Apolipoprotein E4 allele (ApoE4-KI) or Apolipoprotein E3 allele (ApoE3-KI). We exposed 8-week-old male and female ApoE3-KI and ApoE4-KI mice to 0.2% lead acetate via drinking water for 12 weeks and assessed for cognitive behavior deficits during and after the lead exposure. In addition, we exposed a second (cellular) cohort of animals to lead and assessed for changes in adult hippocampal neurogenesis as a potential underlying mechanism for lead-induced learning and memory deficits.

Results

In the behavior cohort, we found that lead reduced contextual fear memory in all animals; however, this decrease was greatest and statistically significant only in lead-treated ApoE4-KI females. Similarly, only lead-treated ApoE4-KI females exhibited a significant decrease in spontaneous alternation in the T-maze. Furthermore, all lead-treated animals developed persistent spatial working memory deficits in the novel object location test, and this deficit manifested earlier in ApoE4-KI mice, with female ApoE4-KI mice exhibiting the earliest deficit onset. In the cellular cohort, we observed that the maturation, differentiation, and dendritic development of adult-born neurons in the hippocampus was selectively impaired in lead-treated female ApoE4-KI mice.

Conclusions

These data suggest that GXE between ApoE4 and lead exposure may contribute to cognitive impairment and that impaired adult hippocampal neurogenesis may contribute to these deficits in cognitive behavior. Together, these data suggest a role for GXE and sex differences in AD risk.

Cadmium impairs the survival and proliferation of cultured adult subventricular neural stem cells through activation of the JNK and p38 MAP kinases

Cadmium (Cd) is a heavy metal with a long biological half-life in humans and is recognized as a toxic pollutant. Cd is also a potential neurotoxicant and its exposure is associated with olfactory impairment in humans. However, the molecular and cellular mechanisms of Cd neurotoxicity are not well defined. Adult neurogenesis is a process that generates functional neurons from adult neural stem/progenitor cells (aNPCs). It occurs in specific regions of the adult brain including the subventricular zone (SVZ) along the lateral ventricles in mammals, a process that is critical for olfaction. Various external stimuli can modulate adult neurogenesis and the effect of neurotoxicants on adult neurogenesis is just beginning to be elucidated. Since Cd exposure can impair olfaction in humans, the goal of this study is to investigate the effects of Cd on SVZ adult neurogenesis and underlying mechanisms using primary cultured SVZ-aNPCs. In this study, we report that low-level Cd exposure decreases cell number, induces apoptosis, and inhibits cell proliferation in SVZ-aNPCs. Furthermore, Cd exposure significantly increases phosphorylation of c-Jun NH2-terminal kinase (JNK), and p38 MAP kinase in these cells, indicative of JNK and p38 activation. Pharmacological inhibition of JNK or p38 MAPK kinases attenuated Cd-induced cell loss and apoptosis. Cd treatment did not cause cell loss or apoptosis in SVZ-aNPCs prepared from transgenic mice null for the neural-specific JNK3 isoform. These data suggest a critical role for p38 and JNK3 MAP kinases in Cd neurotoxicity. These results are, to our knowledge, the first demonstration that Cd impairs SVZ adult neurogenesis in vitro, which may contribute to its neurotoxicity in olfaction.