Vacuum disc phenomenon is a collection of gas in the intervertebral disc space but rarely causes nerve compression. However, some rare type of vacuum phenomenon in the spinal canal may bring about posterior gas displacement within the epidural space. The authors describe two patients with symptomatic epidural gas-containing cyst that seem to be originating from vacuum phenomenon in the intervertebral disc, causing lumbosacral radiculopathy. Radiographic studies demonstrated intervertebral vacuum phenomenon and accumulation of gas in the lumbar epidural space compressing the dural sac and the nerve root. The nerve root in both patients was compressed by gas containing cyst that was surrounded by thin walled capsule separable from the gaseous degenerated disc space. The speculative mechanism of the nerve root compression is discussed. The possibility of gas containing cyst should be considered in case of the nerve root compression in which epidural gas is present.

The material property of the rubber has been studied in order to improve the reliability of the finite element model of a lead rubber bearing (LRB) which is a typical base isolator. Rubber exhibits elastic behaviour even within the large strain range, unlike the general structural material, and has a hyper-elastic characteristics that shows non-linear relationship between load and deformation. This study represents the mechanical characteristics of the rubber by strain energy function in order to develop a finite element (FE) model of LRB. For the study, several strain energy functions were selected and mechanical properties of the rubber were estimated with the energy functions. A finite element model of LRB has been developed by using material properties of rubber and lead which were identified by stress tests. This study estimated the horizontal and vertical force-displacement relationship with the FE model. The adequacy of the FE model was validated by comparing the analytical results with the experimental data.

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Background: The effect of prenatal secondhand smoke (SHS) exposure on childhood atopic dermatitis (AD) remains controversial. We aimed to investigate the association between prenatal SHS and childhood AD in a general population-based birth cohort. Methods: Patients included 2,360 mother–child pairs from the Cohort for Childhood Origin of Asthma and Allergic diseases (COCOA), stratified into 0–3, 4–6, and 7–9 years age groups. Prenatal SHS exposure was assessed using questionnaires. AD diagnosis and symptom assessments were conducted through annual visits by pediatric allergists. Skin prick tests for 18 allergens were conducted. Serum total IgE and eosinophil levels were measured at birth and ages 3 and 7 years. Maternal urine cotinine concentrations were measured at week 36 of gestation. Multivariate logistic regression was performed. Results: Children aged 7–9 years exposed to prenatal SHS were significantly more likely to have an AD diagnosis (aOR 1.670, 95% CI: 0.995–2.804) and current AD (aOR 1.823, 95% CI: 1.051–3.161). This association in AD diagnosis was stronger in children with sensitization (aOR 2.205, 95% CI: 1.048–4.642). Higher maternal urine cotinine levels increased the risk of current AD at ages 4–6 (aOR 2.816, 95% CI: 1.053–7.529). Children exposed to prenatal SHS were more likely to have a late-onset phenotype of AD (aOR 1.663, 95% CI: 1.038–2.664). Conclusion: SHS exposure during pregnancy was associated with late childhood AD. Prevention of prenatal SHS exposure is necessary to reduce the risk of AD in schoolchildren.

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