Feasibility and safety of inserting transient biodegradable stents in the pylorus during pylorus-preserving gastrectomy for gastric cancer: a preliminary study in a porcine for proof of concept

BACKGROUND

To evaluate whether insertion of self-biodegradable stent into the pylorus to prevent delayed-gastric emptying after pylorus-preserving gastrectomy is feasible and safe through porcine experiment.

METHODS

Self-biodegradable dumbbell-shaped pyloric stents were designed from absorbable suture materials: poly(glycolide-co-caprolactone) (PGCL) or poly-p-dioxanone (PPDO). After gastrotomy on ten pigs, each stent was inserted: two shams, four PGCL stents, and four PPDO stents. Body weight (Bwt), body temperature (BT), complete blood cell (CBC) count, and plain X-ray were evaluated. On postoperative day (POD) 13, euthanasia was performed for histologic evaluation.

RESULTS

Operation was successfully performed in all ten pigs. Without tagging suture, both stents migrated before POD 3. The migration was delayed up to POD 13, when the tagging sutures (-t) were applied between stent and stomach wall. Self-degradation of PGCL started from POD 3, and stents were completely excreted from the abdomen by POD 8. Although PPDO were also weakened as self-degradation progressed, its shape was maintained in gastrointestinal tract for 13 days. Unexpected sudden death occurred in the pig with PPDO-t2 on POD 10, which is more likely due to acute volvulus rather than stent-related complication. There was no significant difference between three groups in terms of Bwt, BT, CBC, and histology (sham vs. PGCL vs. PPDO, all p > 0.05).

CONCLUSION

The concept of biodegradable stents made of absorbent suture material seems feasible in porcine experiment. Among them, PGCL which has shown rapid absorption, appears to be a more suitable material for transient pyloric absorbable stent when considering safety aspect.

Female reproductive factors and risk of joint replacement arthroplasty of the knee and hip due to osteoarthritis in postmenopausal women: a nationwide cohort study of 1.13 million women

OBJECTIVES

Previous studies of the relationships between female reproductive factors and osteoarthritis (OA) have shown conflicting results. In this study, we aimed to explore the relationships between reproductive factors and joint replacement arthroplasty of the knee (TKRA) and hip (THRA) in a large nationwide population-based cohort of postmenopausal Korean women.

METHODS

We included 1,134,680 subjects who participated in national health examinations in 2009 in the study. The study outcomes were incident THRA or TKRA due to severe hip or knee OA. The relationships between reproductive factors and THRA or TKRA were evaluated using a multivariable-adjusted proportional hazards model.

RESULTS

During a mean follow-up duration of 8.2 years, 1,610 incident THRA cases and 60,670 incident TKRA cases were observed. Later age at menarche, longer breastfeeding, HRT and OC use were associated with increased risk of TKRA for severe knee OA, while later age at menopause and longer reproductive span were associated with decreased risk. With regard to THRA for severe hip OA, later menarche, longer breastfeeding, HRT more than 5 years, and OC use more than 1 year were associated with higher risk. The associations between reproductive factors and severe OA were more pronounced in underweight and younger subjects.

CONCLUSION

We found that shorter estrogen exposure was associated with higher risk of TKRA due to severe knee OA, and such associations were more pronounced in underweight and younger subjects. The association between shorter estrogen exposure and THRA was not robust.

Female reproductive factors and the risk of dementia: a nationwide cohort study

BACKGROUND AND PURPOSE

The aim was to investigate whether female reproductive factors are associated with dementia.

METHODS

In all, 4 696 633 post-menopausal women without dementia were identified using the Korean National Health Insurance System database. Data on reproductive factors were collected using a self-administered questionnaire. Dementia was determined using dementia diagnosis codes and anti-dementia drug prescription. Cox proportional hazards regression was conducted to assess the hazard ratio (HR) for dementia according to reproductive factors.

RESULTS

During a median follow-up of 5.74 years, there were 212 227 new cases of all-cause dementia (4.5%), 162 901 cases of Alzheimer's disease (3.5%) and 24 029 cases of vascular dementia (0.5%). The HR of dementia was 1.15 [95% confidence interval (CI) 1.03-1.16] for menarcheal age ≥17 years compared with menarcheal age 13-14 years, 0.79 (0.77-0.81) for menopausal age ≥55 years compared with menopausal age <40 years, and 0.81 (0.79-0.82) for fertility duration ≥40 years compared with fertility duration <30 years. Whilst being of parity one (HR 0.89, 95% CI 0.85-0.94) and breastfeeding <6 months (HR 0.92, 95% CI 0.88-0.95) was associated with lower risk of dementia, being of parity two or more (HR 1.04, 95% CI 0.99-1.05) and breastfeeding ≥12 months (HR 1.14, 95% CI 1.01-1.07) was associated with a higher risk of dementia than women without parity or breastfeeding history. Use of hormone replacement therapy and oral contraceptives independently reduced the dementia risk by 15% and 10%, respectively.

CONCLUSIONS

Female reproductive factors are independent risk factors for dementia incidence, with higher risk associated with shorter lifetime endogenous estrogen exposure.

Black TiO2 nanotubes: Efficient electrodes for triggering electric field-induced stimulation of stem cell growth

TiO₂ nanostructures represent a key platform for biomedical applications, due to the combination of biocompatibility and high surface area. Especially TiO₂ nanotube layers have been widely investigated due to controllable nanotopographic effects as well as for electrodes in electrostimulation experiments. In the present work we produce Ar/H₂-reduced 'black' TiO₂ nanotube arrays with a strongly enhanced electrical conductivity and explore their interaction with mesenchymal stem cells when used as electrodes to apply electric fields (EF) across the cells. While we observe no significant change in cell adhesion and their focal contact formation on these high conductivity nanotubes, we do observe a rapid stem cell response when EF is engaged using the 'black' TiO₂ nanotube arrays as electrodes. Compared to as-formed nanotube arrays, a faster stem cell growth was observed and a lower EF intensity caused an intracellular calcium level elevation. Our results indicate that the increased conductivity in TiO₂ nanotubes significantly enhances the early stem cell response to minimal electric field stimuli. STATEMENT OF SIGNIFICANCE: The use of TiO₂ nanostructures in biomedical applications is widely investigated, especially considering the nanostructured surface influence on the biomaterial-cell interactions. We have previously shown that an applied electric field (EF) on stem cells grown on TiO₂ nanotubes leads to synergistic osteogenic stimulation in the absence of biochemical bone-inducing supplements. Here we report that black (i.e. highly conductive nanotubes obtained by reduction treatments) TiO₂ nanotubes enable short-time EF effects on stem cells: we observe a faster stem cell growth and a significantly enhanced early stem cell response to minimal EF stimuli. The application of such nanostructures under electric field is promising for therapeutic interventions for bone regeneration and tissue engineering approaches.

ROS-dependent HMGB1 secretion upregulates IL-8 in upper airway epithelial cells under hypoxic condition

High-mobility group box 1 (HMGB1) mediates various functions according to the location. We tried to investigate the role of HMGB1 in upper airway under hypoxic conditions. We cultured primary normal human nasal epithelium (NHNE) cells under hypoxic conditions and evaluated the movement of HMGB1 by western blotting, immunofluorescence, and enzyme-linked immunosorbent assay (ELISA). Reactive oxygen species (ROS) level was evaluated to estimate the translocation mechanism of HMGB1. The role of secreted HMGB1 was evaluated by ELISA assay. Furthermore, we collected human nasal mucosa samples and nasal lavage fluids from patients conditioned under hypoxic and non-hypoxic environment, and compared the expression of HMGB1 in human nasal mucosa samples by immunohistochemistry and the levels of HMGB1 in lavage fluids using ELISA assay. Hypoxia induced translocation of HMGB1 into the extracellular area and it was dependent on ROS produced by dual oxidase 2. Secreted HMGB1 was involved in the upregulation of interleukin (IL)-8. In human samples, HMGB1 was translocated from nucleus to the cytoplasm in hypoxic-conditioned nasal mucosa. HMGB1 was increased in nasal lavage samples of chronic rhinosinusitis patients, whose sinus mucosa was supposed to be hypoxic as compared with controls. We suggest that HMGB1 is secreted in hypoxic condition via ROS-dependent mechanism and secreted HMGB1 participates in IL-8 upregulation mediating inflammatory response.

Diverse bitter stimuli elicit highly similar patterns of Fos-like immunoreactivity in the nucleus of the solitary tract

Previous studies have demonstrated that oral stimulation with quinine elicits Fos-like immunoreactivity in the first-order gustatory nucleus, the NST, with a different topographic distribution than sucrose or citric acid. However, it is unknown whether the quinine pattern is unique to this alkaloid or common across bitter stimuli with different chemical structures. Indeed, recent physiological experiments suggest that taste receptor cells and primary afferent neurons may exhibit selectivity for various bitter tastants. The present investigation compared the distribution of FLI in NST following stimulation with three bitter chemicals: QHCl, denatonium and propylthiouracil, stimuli that evoked Ca(2+) currents in almost entirely different sets of receptor cells. The results demonstrate that the quinine pattern is not idiosyncratic but instead generalizes to the other two tastants. Although it remains possible that intermingled but different NST neurons are activated by these stimuli, these data suggest that a specialized region in the NST is preferentially involved in processing a common aspect of bitter tastants. In contrast to citric acid, quinine, denatonium and propylthiouracil all elicited vigorous oromotor rejection responses, consistent with our earlier hypothesis that the medial third of the NST may be an afferent trigger zone for oromotor rejection.

Allergen-specific immunosuppression by ovalbumin fused with diphtheria toxin in mice sensitized with albumins of different origin

BACKGROUND

We previously reported that ovalbumin-diphtheria toxin (OVA-DT) fusion protein eliminates mast cells bearing OVA-specific IgE and protects OVA-sensitized mice from fatal anaphylaxis induced by OVA challenge.

OBJECTIVE

To prove the specificity of therapeutic effect of OVA-DT to allergy induced by OVA only and not by other allergens such as human serum albumin (HSA), and to examine the cytotoxic effect of OVA-DT on B cells bearing OVA-specific IgE.

METHODS

Mice were sensitized with two different antigens, OVA and HSA, and then treated with OVA-DT. The therapeutic effect of OVA-DT on the allergy response to each of allergen was evaluated by anaphylactic test. The effect of OVA-DT on the production of allergen-specific Ig isotypes of the sensitized mice and the cytotoxic effect of OVA-DT on B cells expressing OVA-specific IgE were examined.

RESULTS

OVA-DT suppressed only OVA-induced allergy but not HSA-induced allergy in mice sensitized with a mixture of OVA and HSA. The suppression was prolonged even to the mice boosted with the same allergen 14 days after last treatment of OVA-DT. In addition, when the sensitized mice were boosted with the same allergens 14 days after last treatment of OVA-DT, the mice showed to increase the production of OVA-specific IgG2a/IgG3 and decreased that of OVA-specific IgE. OVA-DT targeted B cells bearing OVA-specific IgE, and killed them by DT-mediated cytotoxicity.

CONCLUSION

The therapeutic effect of OVA-DT was specific to OVA-induced allergy and the suppression of OVA-induced allergy was continuously shown in the mice boosted with the same allergens. This is considered to be caused by the increase of OVA-specific IgG2a and IgG3, and because of the decrease of OVA-specific IgE by killing of B cells bearing OVA-specific IgE.

Tumor necrosis factor receptor 2 polymorphism in systemic lupus erythematosus: no association with disease

Genetic factors and immune dysregulation play important roles in the development of systemic lupus erythematosus (SLE). Tumor necrosis factor receptor 2 (TNFR2) is suggested to be involved in the development of SLE because its genetic locus (1p36) encompasses one of the susceptible loci for SLE and its ligand (TNF) is associated with SLE. To investigate the role of TNFR2 in the pathogenesis of SLE, 139 Korean patients were genotyped with SLE, 137 healthy control subjects were genotyped for TNFR2 196 R/M polymorphism in exon 6 with PCR-SSCP, and the clinical characteristics of SLE were analyzed according to the genotypes. The genotype frequencies of 196 R/R, 196 R/M, and 196 M/M were 3.6%, 30.9%, and 65.5% in SLE patients and 4.4%, 26.3%, and 69.3% in healthy controls (p = 0.676). The allelic frequency of 196 R was 19.1% in SLE patients and 17.5% in healthy controls (p = 0.638, odds ratio = 1.109, and the 95% confidence interval = 0.720-1.708). The clinical characteristics were not different according to the genotypes. In conclusion, no skewed distribution of TNFR2 196 R/M polymorphism was found in Korean patients with SLE compared with healthy controls. Further studies in other populations will be needed to elucidate the role of the TNFR2 polymorphism in the development of SLE.

Localized pigmented villonodular synovitis of the knee: arthroscopic treatment

Pigmented villonodular synovitis (PVNS) is a relatively rare condition. It occurs in two forms: a diffuse form involves the entire synovium and occurs in the majority of cases, and a localized form involves a discrete section of the synovium. The disorder almost always involves a single joint and the knee is most commonly affected. We report on three cases of localized PVNS that involved the patellar fat pad and synovium. Diagnostic and therapeutic arthroscopies were performed, and typical localized PVNS was found. Complete resection of the lesions was performed arthroscopically. Arthroscopy can be used as an effective diagnostic and therapeutic tool for identification and treatment of intra-articular localized PVNS of the knee.