Finite element modeling and analysis of effect of preexisting cervical degenerative disease on the spinal cord during flexion and extension

Recent studies have emphasized the importance of dynamic activity in the development of myelopathy. However, current knowledge of how degenerative factors affect the spinal cord during motion is still limited. This study aimed to investigate the effect of various types of preexisting herniated cervical disc and the ligamentum flavum ossification on the spinal cord during cervical flexion and extension. A detailed dynamic fluid-structure interaction finite element model of the cervical spine with the spinal cord was developed and validated. The changes of von Mises stress and maximum principal strain within the spinal cord in the period of normal, hyperflexion, and hyperextension were investigated, considering various types and grades of disc herniation and ossification of the ligamentum flavum. The flexion and extension of the cervical spine with spinal canal encroachment induced high stress and strain inside the spinal cord, and this effect was also amplified by increased canal encroachments and cervical hypermobility. The spinal cord might evade lateral encroachment, leading to a reduction in the maximum stress and principal strain within the spinal cord in local-type herniation. Although the impact was limited in the case of diffuse type, the maximum stress tended to appear in the white matter near the encroachment site while compression from both ventral and dorsal was essential to make maximum stress appear in the grey matter. The existence of canal encroachment can reduce the safe range for spinal cord activities, and hypermobility activities may induce spinal cord injury. Besides, the ligamentum flavum plays an important role in the development of central canal syndrome.Significance. This model will enable researchers to have a better understanding of the influence of cervical degenerative diseases on the spinal cord during extension and flexion.

Effect of Different Types of Ossification of the Posterior Longitudinal Ligament on the Dynamic Biomechanical Response of the Spinal Cord: A Finite Element Analysis

Ossification of the posterior longitudinal ligament (OPLL) has been identified as an important cause of cervical myelopathy. However, the biomechanical mechanism between the OPLL type and the clinical characteristics of myelopathy remains unclear. The aim of this study was to evaluate the effect of different types of OPLL on the dynamic biomechanical response of the spinal cord. A three-dimensional finite element model of the fluid-structure interaction of the cervical spine with spinal cord was established and validated. The spinal cord stress and strain, cervical range of motion (ROM) in different types of OPLL models were predicted during dynamic flexion and extension activity. Different types of OPLL models showed varying degrees of increase in stress and strain under the process of flexion and extension, and there was a surge toward the end of extension. Larger spinal cord stress was observed in segmental OPLL. For continuous and mixed types of OPLL, the adjacent segments of OPLL showed a dramatic increase in ROM, while the ROM of affected segments was limited. As a dynamic factor, flexion and extension of the cervical spine play an amplifying role in OPLL-related myelopathy, while appropriate spine motion is safe and permitted. Segmental OPLL patients are more concerned about the spinal cord injury induced by large stress, and patients with continuous OPLL should be noted to progressive injuries of adjacent level.

The biomechanical effect of different types of ossification of the ligamentum flavum on the spinal cord during cervical dynamic activities

Ossification of the ligamentum flavum (OLF) is thought to be an influential etiology of myelopathy, as thickened ligamentum flavum causes the stenosis of the vertebral canal, which could subsequently compress the spinal cord. Unfortunately, there was little information available on the effects of cervical OLF on spinal cord compression, such as the relationship between the progression of cervical OLF and nervous system symptoms during dynamic cervical spine activities. In this research, a finite element model of C1-C7 including the spinal cord featured by dynamic fluid-structure interaction was reconstructed and utilized to analyze how different types of cervical OLF affect principal strain and stress distribution in spinal cord during spinal activities towards six directions. For patients with cervical OLF, cervical extension induces higher stress within the spinal cord among all directions. From the perspective of biomechanics, extension leads to stress concentration in the lateral corticospinal tracts or the posterior of gray matter. Low energy damage to the spinal cord would be caused by the high and fluctuating stresses during cervical movements to the affected side for patients with unilateral OLF at lower grades.

Impacts of Climate Changes on Geographic Distribution of Primula filchnerae, an Endangered Herb in China

Primula filchnerae, an endangered plant endemic to China, has drawn people's attention in recent years due to its ornamental value in flower. It was rarely recorded since being described in 1902, but it was rediscovered in 2009 and is now known from a limited number of sites located in Hubei and Shaanxi Provinces. Since the species is still poorly known, a number of unanswered questions arise related to it: How has P. filchnerae responded to past climate change and how might it respond in the future? Why was P. filchmerae so rarely collected during the past century? We assembled geographic coordinates for P. filchnerae through the field surveys and website searches, and then used a maximum entropy model (MaxEnt) to simulate its potential suitable distribution in six periods with varied carbon emission levels by combining bioclimatic and environmental factors. MaxEnt showed that Min Temperature of the Coldest Month (bio6) and Precipitation of the Coldest Quarter (bio19) affected P. filchnerae's distribution most, with an aggregate contribution >60% and suitable ranges above -5 °C and below 40 mm, respectively. We also analyzed potential habitat distribution in various periods with differing impacts of climate change compared to today's suitable habitats, and in most cases, Shaanxi and Sichuan remained the most stable areas and with possible expansion to the north under various carbon emission scenarios, but the 2050s SSP5-8.5 scenario may be an exception. Moreover, we used MaxEnt to evaluate population shifts, with various scenarios indicating that geometric center would be concentrated in Sichuan Province in China. Finally, conservation strategies are suggested, including the creation of protected areas, long-term monitoring, raising public awareness of plant conservation, situ conservation measures, assisted migration, and species introduction. This study demonstrates how P. filchnerae may have adapted to changes in different periods and provides a scientific basis for germplasm conservation and management.

Biomechanical response of lumbar intervertebral disc in daily sitting postures: a poroelastic finite element analysis

This study aims to establish and validate a poroelastic L4-L5 finite element model to evaluate the effect of different sitting postures and their durations on the mechanical responses of the disc. During the sustained loading conditions, the height loss, fluid loss and von-Mises stress gradually increased, but the intradiscal pressure decreased. The varying rates of aforementioned parameters were more significant at the initial loading stage and less so at the end. The predicted values in the flexed sitting posture were significantly greater than other postures. The extended sitting posture caused an obvious von-Mises stress concentration in the posterior region of the inter-lamellar matrix. From the biomechanical perspective, prolonged sitting may pose a high risk of lumbar disc degeneration, and therefore adjusting the posture properly in the early stage of sitting time may be useful to mitigate that. Additionally, upright sitting is a safer posture, while flexed sitting posture is more harmful.

Potential of electronic devices for detection of health problems in older adults at home: A systematic review and meta-analysis

OBJECTIVE

The aim of this review was to evaluate the overall diagnostic performance of e-devices for detection of health problems in older adults at home.

METHODS

A systematic review was conducted following the PRISMA-DTA guidelines.

RESULTS

31 studies were included with 24 studies included in meta-analysis. The included studies were divided into four categories according to the signals detected: physical activity (PA), vital signs (VS), electrocardiography (ECG) and other. The meta-analysis showed the pooled estimates of sensitivity and specificity were 0.94 and 0.98 respectively in the 'VS' group. The pooled sensitivity and specificity were 0.97 and 0.98 respectively in the 'ECG' group.

CONCLUSIONS

All kinds of e-devices perform well in diagnosing the common health problems. While ECG-based health problems detection system is more reliable than VS-based ones. For sole signal detection system has limitation in diagnosing specific health problems, more researches should focus on developing new systems combined of multiple signals.

Effect of home-based exercise programs with e-devices on falls among community-dwelling older adults: a meta-analysis

Aim: To explore the effectiveness of home-based exercise programs with e-devices (HEPEs) on falls among community-dwelling older adults. Methods: Twelve randomized controlled trials were included in the meta-analysis considering four fall-related outcomes. Results: HEPEs significantly reduced the rate of falls (risk ratio: 0.82; 95% CI: 0.72-0.95; p = 0.006) and improved lower extremity strength (mean difference: -0.94; 95% CI: -1.71 to -0.47; p < 0.001). There was a significant improvement favoring HEPEs on balance if the participants were aged >75 years (mean difference: -0.55; 95% CI: -1.05 to -0.05; p = 0.03), or the intervention duration was at least 16 weeks (mean difference: -0.81; 95% CI: -1.58 to -0.05; p = 0.04). Conclusion: HEPEs demonstrated an overall positive effect on falls among community-dwelling older adults.

Maximum Entropy Modeling the Distribution Area of Morchella Dill. ex Pers. Species in China under Changing Climate

Morchella is a kind of precious edible, medicinal fungi with a series of important effects, including anti-tumor and anti-oxidation effects. Based on the data of 18 environmental variables and the distribution sites of wild Morchella species, this study used a maximum entropy (MaxEnt) model to predict the changes in the geographic distribution of Morchella species in different historical periods (the Last Glacial Maximum (LGM), Mid Holocene (MH), current, 2050s and 2070s). The results revealed that the area under the curve (AUC) values of the receiver operating characteristic curves of different periods were all relatively high (>0.83), indicating that the results of the maximum entropy model are good. Species distribution modeling showed that the major factors influencing the geographical distribution of Morchella species were the precipitation of the driest quarter (Bio17), elevation, the mean temperature of the coldest quarter (Bio11) and the annual mean temperature (Bio1). The simulation of geographic distribution suggested that the current suitable habitat of Morchella was mainly located in Yunnan, Sichuan, Gansu, Shaanxi, Xinjiang Uygur Autonomous Region (XUAR) and other provinces in China. Compared with current times, the suitable area in Northwest and Northeast China decreased in the LGM and MH periods. As for the future periods, the suitable habitats all increased under the different scenarios compared with those in contemporary times, showing a trend of expansion to Northeast and Northwest China. These results could provide a theoretical basis for the protection, rational exploitation and utilization of wild Morchella resources under scenarios of climate change.

Multiple roles of mothers against decapentaplegic homolog 4 in tumorigenesis, stem cells, drug resistance, and cancer therapy

The transforming growth factor (TGF)-β signaling pathway controls many cellular processes, including proliferation, differentiation, and apoptosis. Abnormalities in the TGF-β signaling pathway and its components are closely related to the occurrence of many human diseases, including cancer. Mothers against decapentaplegic homolog 4 (Smad4), also known as deleted in pancreatic cancer locus 4, is a typical tumor suppressor candidate gene locating at q21.1 of human chromosome 18 and the common mediator of the TGF-β/Smad and bone morphogenetic protein/Smad signaling pathways. It is believed that Smad4 inactivation correlates with the development of tumors and stem cell fate decisions. Smad4 also interacts with cytokines, miRNAs, and other signaling pathways, jointly regulating cell behavior. However, the regulatory function of Smad4 in tumorigenesis, stem cells, and drug resistance is currently controversial. In addition, Smad4 represents an attractive therapeutic target for cancer. Elucidating the specific role of Smad4 is important for understanding the mechanism of tumorigenesis and cancer treatment. Here, we review the identification and characterization of Smad4, the canonical TGF-β/Smad pathway, as well as the multiple roles of Smad4 in tumorigenesis, stem cells, and drug resistance. Furthermore, we provide novel insights into the prospects of Smad4-targeted cancer therapy and the challenges that it will face in the future.

Total Flavones of Abelmoschus manihot Ameliorates Podocyte Pyroptosis and Injury in High Glucose Conditions by Targeting METTL3-Dependent m6A Modification-Mediated NLRP3-Inflammasome Activation and PTEN/PI3K/Akt Signaling

Background: The total flavones of Abelmoschus manihot (TFA), a compound that is extracted from Abelmoschus manihot, has been widely used in China to reduce podocyte injury in diabetic kidney disease (DKD). However, the mechanisms underlying the therapeutic action of this compound have yet to be elucidated. Podocyte pyroptosis is characterized by activation of the NLRP3 inflammasome and plays an important role in inflammation-mediated diabetic kidneys. Regulation of the PTEN/PI3K/Akt pathway is an effective strategy for improving podocyte damage in DKD. Previous research has also shown that N6-methyladenosine (m6A) modification is involved in DKD and that m6A-modified PTEN regulates the PI3K/Akt pathway. In this study, we investigated whether TFA alleviates podocyte pyroptosis and injury by targeting m6A modification-mediated NLRP3-inflammasome activation and PTEN/PI3K/Akt signaling. Methods: We used MPC-5 cells under high glucose (HG) conditions to investigate the key molecules that are involved in podocyte pyroptosis and injury, including activation of the NLRP3 inflammasome and the PTEN/PI3K/Akt pathway. We detected alterations in the levels of three methyltransferases that are involved in m6A modification. We also investigated changes in the levels of these key molecules in podocytes with the overexpression or knockdown of methyltransferase-like (METTL)3. Results: Analysis showed that TFA and MCC950 protected podocytes against HG-induced pyroptosis and injury by reducing the protein expression levels of gasdermin D, interleukin-1β, and interleukin-18, and by increasing the protein expression levels of nephrin, ZO-1, WT1 and podocalyxin. TFA and 740Y-P inhibited activation of the NLRP3 inflammasome via the PI3K/Akt pathway by inhibiting the protein levels of NIMA-related kinase7, NLRP3, ASC, and caspase-1, and by increasing the protein expression levels of p-PI3K and p-Akt. TFA improved pyroptosis and injury in HG-stimulated podocytes by regulating METTL3-dependent m6A modification. Conclusion: Collectively, our data indicated that TFA could ameliorate pyroptosis and injury in podocytes under HG conditions by adjusting METTL3-dependent m6A modification and regulating NLRP3-inflammasome activation and PTEN/PI3K/Akt signaling. This study provides a better understanding of how TFA can protect podocytes in DKD.

[Inner hair cells loss by carboplatin and the changes of cochlear compound action potential in chinchillas]

Objective: To measure the cochlear compound action potential (CAP) and the densities of hair cells (HCs) along the whole length of the basilar membrane (BM) in adult chinchillas. And to investigate the relationship between the severity of inner hair cells (IHCs) loss and the changes of CAP by using carboplatin-cochlear lesion model. Methods: Totally 18 chinchillas were recruited after ontological evaluation. They were randomly divided into three groups (with 6 subjects in each), A: control, B and C: legion groups treated with one or two shot(s) of carboplatin respectively (76 mg/kg in one shot, i.p., one-week interval between the two shots). Endpoint tests were performed 30 days after the carboplatin treatment in groups B and C, and matched time in group A. A sliver-ball electrode was placed into round window niche via hypotympanic approach in anesthetized chinchilla. CAP was measured in response to clicks and tone burst of 0.5, 1, 2, 4, 8, 16 kHz respectively under anesthesia. CAP amplitudes and thresholds were measured and compared across the groups. After the recording, the whole cochlea surface preparation was made and the HCs were stained in histochemistry against substrate of succinate dehydrogenase (SDH). Images were taken with high-resolution digital camera under light microscope and across the whole cochlea. The length of the basilar membrane (BM) and the number of both IHCs and OHCs were counted. The HC density was calculated as the number of HCs per 10% BM length. Results: The CAP thresholds were (7.1±2.6), (25.4±5.0), (24.6±5.4), (10.4±5.0), (0.4±1.4), (4.2±6.3) and (17.1±14.1) dB SPL (from 6 subjects in group A, n=12 ears) corresponding to stimuli of Click and 0.5, 1, 2, 4, 8, 16 kHz tone bursts respectively. The total number of cochlear HCs were measured as (8 936±643) (x±s) and the average length of the BMs was (17.73±1.012) mm from the six subjects in the group A (n=12 ears). The HC density was found to be varied slightly across the BM. There was no significant CAP threshold difference between the control (group A) and the group B, which received one shot of carboplatin. However, the maximal CAP amplitude was reduced by 40% in the group B and compared with group A. Correspondingly, approximately 40% loss of IHCs were seen. In contrast, a significant CAP threshold shift was seen in subjects receiving two shots of carboplatin (group C), which was accompanied by a loss of 90% IHCs. Conclusions: The CAP thresholds of adult chinchillas show typical open-V shape with the lowest values at 2, 4, and 8 kHz. IHC loss by carboplatin in certain degree is well correlated with CAP amplitude reduction, but does not change the threshold when inner hair cell loss reaches 40%, however, if inner hair cell loss exceeds 80%, the threshold shift of CAP will be inevitable.

The Role of Mitochondrial Dynamics and Mitophagy in Carcinogenesis, Metastasis and Therapy

Mitochondria are key cellular organelles and play vital roles in energy metabolism, apoptosis regulation and cellular homeostasis. Mitochondrial dynamics refers to the varying balance between mitochondrial fission and mitochondrial fusion that plays an important part in maintaining mitochondrial homeostasis and quality. Mitochondrial malfunction is involved in aging, metabolic disease, neurodegenerative disorders, and cancers. Mitophagy, a selective autophagy of mitochondria, can efficiently degrade, remove and recycle the malfunctioning or damaged mitochondria, and is crucial for quality control. In past decades, numerous studies have identified a series of factors that regulate mitophagy and are also involved in carcinogenesis, cancer cell migration and death. Therefore, it has become critically important to analyze signal pathways that regulate mitophagy to identify potential therapeutic targets. Here, we review recent progresses in mitochondrial dynamics, the mechanisms of mitophagy regulation, and the implications for understanding carcinogenesis, metastasis, treatment, and drug resistance.

[The clinical characteristics and treatment outcomes of 386 patients with hypopharyngeal cancer]

OBJECTIVE

To investigate the clinical characteristics, surgical treatment outcomes and prognostic factors of hypopharyngeal carcinoma.

METHODS

A retrospective review of the Eye & ENT Hospital of Fudan University patients' database between January 2003 and June 2013 was conducted and a total of 386 patients were enrolled in the study. Patients' clinical and oncological information was collected and survival rates were analyzed using Kaplan-Meier curves. Prognostic factors were evaluated with multivariate Cox model survival analysis.

RESULTS

Among the 386 patients 95.9% were males and 4.1% were females, with an average age of (58.4±9.4) years. The primary tumor sites were pyriform sinus (76.7%), posterior hypopharyngeal wall (17.3%) and postcricoid region (6.0%). There were 31(8.0%), 83(21.5%), 175(45.3%) and 97(25.1%) patients with stage T1 to T4, respectively, 99(25.6%), 74(19.2%), 181(46.9%) and 32(8.3%) patients with stage N0 to N3, respectively , and 3 patients with distant metastasis to lung on initial diagnosis. Second primary cancers were found in 28 cases (7.3%). The 5-year overall survival (OS), disease specific survival (DSS) and disease free survival (DFS) were 45.8%, 48.1% and 46.0% respectively according to Kaplan-Meier survival curves. Multivariate Cox regression model showed significant association between 5-year overall survival rate and T stage (P<0.001), N stage (P=0.003) and second primary tumors (P=0.017). Advanced T stage and lymphovascular invasion were associated with a higher rate of recurrence (P<0.001).

CONCLUSIONS

Hypopharyngeal squamous cell carcinoma has a dismal prognosis, with high rates of submucosal infiltration, cervical lymph node metastasis and distant metastasis. Treatment choices should be made according to TNM stage and overall health conditions in order to achieve ideal oncologic and functional results. Surgery with postoperative chemoradiation therapy is the main treatment for advanced-stage hypopharyngeal cancer.

Isolation of CHS Gene from Brunfelsia acuminata Flowers and Its Regulation in Anthocyanin Biosysthesis

Chalcone synthase gene (BaCHS) from Brunfelsia acuminata flowers was isolated using RT-PCR and RACE. The coding region of the gene is 1425-bp with an open reading frame of 1170-bp, 73-bp 5'UTR, and 172-bp 3'UTR. Its deduced protein does not have a signal peptide but does contain a cond_enzyme superfamily domain, and consists of 389 amino acids with a predicted molecular mass of 42,699 Da and a pI of 6.57. The deduced amino acid sequence of BaCHS shares 90%, 88%, 85%, 84% and 79% identity with CHS from Petunia hybrida, Nicotiana tabacum, Solanum lycopersicum, Capsicum annuum and Camellia sinensis, respectively. The striking color change from dark purple to light purple and ultimately lead to pure white resulted from a decline in anthocyanin content of the petals and was preceded by a decrease in the expression of BaCHS. Its gene expression was positively correlated with the contents of anthocyanin (p ≤ 0.01).

Evaluation of a loop-mediated isothermal amplification method for the rapid detection of Vibrio harveyi in cultured marine shellfish

AIMS

The purpose of this study was to establish a loop-mediated isothermal amplification (LAMP) method for the rapid, sensitive detection of Vibrio harveyi in mariculture shellfish.

METHODS AND RESULTS

A set of four primers, two outer and two inner primers, were designed from the toxR gene sequence of V. harveyi. The LAMP reaction was conducted at 65 degrees C for 60 min. There were no cross-reactions with other bacterial strains indicating a high specificity of the LAMP. The detection sensitivity of the LAMP assay for V. harveyi with both of pure cultures and added shellfish cultures is about 10(-5) dilution level (equivalent to 17.2 cells per reaction). The amplification products were detected by visual inspection using SYBR Green I. The detection sensitivity using the LAMP method was 10 times higher than that of conventional PCR.

CONCLUSIONS

The LAMP assay established in this study is an extremely specific, sensitive and rapid for identification of V. harveyi in mariculture shellfish.

SIGNIFICANCE AND IMPACT OF THE STUDY

This LAMP technique provides an important detecting tool for the detection of V. harveyi infection both in the laboratory and field. This technique is recommended as an applied protocol for health management programme and disease surveillance of in hatcheries as well as in grow-out pond, to prevent the disease outbreak.