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Abstract Background Lumbar disc herniation (LDH) is the main clinical cause of low back pain. The pathogenesis of lumbar disc herniation is still uncertain, while it is often accompanied by disc rupture. In order to explore relationship between loading rate and failure mechanics that may lead to lumbar disc herniation, the failure mechanical properties of the intervertebral disc under high rates of loading were analyzed. Method Bend the lumbar motion segment of a healthy sheep by 5° and compress it to the ultimate strength point at a strain rate of 0.008/s, making a damaged sample. Within the normal strain range, the sample is subjected to quasi-static loading and high loading rate at different strain rates. Results For healthy samples, the stress–strain curve appears collapsed only at high rates of compression; for damaged samples, the stress–strain curves collapse both at quasi-static and high-rate compression. For damaged samples, the strengthening stage becomes significantly shorter as the strain rate increases, indicating that its ability to prevent the destruction is significantly reduced. For damaged intervertebral disc, when subjected to quasi-static or high rates loading until failure, the phenomenon of nucleus pulposus (NP) prolapse occurs, indicating the occurrence of herniation. When subjected to quasi-static loading, the AF moves away from the NP, and inner AF has the greatest displacement; when subjected to high rates loading, the AF moves closer to the NP, and outer AF has the greatest displacement. The Zhu–Wang–Tang (ZWT) nonlinear viscoelastic constitutive model was used to describe the mechanical behavior of the intervertebral disc, and the fitting results were in good agreement with the experimental curve. Conclusion Experimental results show that, both damage and strain rate have a significant effect on the mechanical behavior of the disc fracture. The research work in this article has important theoretical guiding significance for preventing LDH in daily life.

Vaccination against human papilloma virus (HPV) prevents HPV infections and HPV-related cancers. Most countries currently use a two-dose HPV vaccination schedule, but a growing number of studies have found potential effectiveness of single-dose HPV vaccine, sparking a debate about the feasibility of switching from a two-dose regimen to a single-dose regimen in the global vaccine community. Given the large global disease burden of cervical cancer and inequality between countries and regions due to the tight HPV vaccine supply, World Health Organization Strategic Advisory Group of Experts on Immunization (SAGE) stated that single-dose schedules provide comparable protection to the two- or three-dose schedules at a relevant meeting in April 2022. In this article, we review current status of HPV vaccination and researches on the single-dose HPV vaccine protection, and analyze the opportunity and challenges for single-dose HPV vaccination strategy in the future.

ObjectivesTo quantify the burden and variation trends of cancers in children under 5 years at the global, regional, and national levels from 1990 to 2019.MethodsEpidemiological data for children under 5 years who were diagnosed with any one childhood cancer were obtained from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) from 1990 to 2019. The outcomes were the absolute numbers and rates of incidence, prevalence, mortality, and disability-adjusted life-years (DALYs) for different types of cancer.ResultsIn 2019, 8,774,979.1 incident cases (95% uncertainty interval [UI]: 6,243,599.2 to11,737,568.5) and 8,956,583.8 (6,446,323.9 to 12,364,520.8) prevalent cases of cancer in children under 5 years were identified worldwide; these cancers resulted in 44,451.6 (36,198.7 to 53,905.9) deaths and 3,918,014.8 (3,196,454.9 to 4,751,304.2) DALYs. From 1990 to 2019, although the numbers of incident and prevalent cases only decreased by −4.6% (−7.0 to −2.2) and −8.3% (−12.6 to −3.4), respectively, the numbers of deaths and DALYs clearly declined by −47.8% (−60.7 to −26.4) and −47.7% (−60.7 to −26.2), respectively. In 2019, the middle sociodemographic index (SDI) regions had the highest incidence and prevalence, whereas the low SDI regions had the most mortality and DALYs. Although all of the SDI regions displayed a steady drop in deaths and DALYs between 1990 and 2019, the low-middle and low SDI regions showed increasing trends of incidence and prevalence. Leukemia remained the most common cancer globally in 2019. From 1990 to 2019, the burdens of leukemia, liver cancer, and Hodgkin's lymphoma declined, whereas the incidence and prevalence of other cancers grew, particularly testicular cancer.ConclusionsThe global childhood cancer burden in young children has been steadily decreasing over the past three decades. However, the burdens and other characteristics have varied across different regions and types of cancers. This highlights the need to reorient current treatment strategies and establish effective prevention methods to reduce the global burden of childhood cancer.