Fabrication and characterization of hydrophilic poly(lactic-co-glycolic acid)/poly(vinyl alcohol) blend cell scaffolds by melt-molding particulate-leaching method

Porous PLGA/PVA scaffolds were fabricated by blending poly(lactic-co-glycolic acid) (PLGA) with polyvinyl alcohol (PVA) to improve the hydrophilicity and cell compatibility of the scaffolds for tissue engineering applications. PLGA/PVA blend scaffolds with different PVA compositions up to 20wt% were fabricated by a melt-molding particulate-leaching method (non-solvent method). The prepared scaffolds were investigated by scanning electron microscopy (SEM), mercury intrusion porosimetry, the measurements of water contact angles and bi-axial tensile strengths, etc. for their surface and bulk characterizations. The scaffolds exhibited highly porous and open-cellular pore structures with almost same surface and interior porosities (pore size, 200-300 microm; porosity, about 90%). The PLGA/PVA blend scaffolds with PVA compositions more than 5% were easily wetted in cell culture medium without any prewetting treatments, which is highly desirable for tissue engineering applications. In vitro cell compatibility of the control hydrophobic PLGA and hydrophilized PLGA/PVA (5wt%) blend scaffolds was compared by the culture of human chondrocytes in the scaffolds and the following analyses by MTT assay and SEM observation. It was observed that the PLGA/PVA blend scaffold had better cell adhesion and growth than the control PLGA scaffold. For in vivo evaluation of tissue compatibility, the scaffolds were implanted into the skull defects of rabbits. The results were evaluated by histology examinations. The PLGA/PVA (5wt%) blend scaffold showed better bone ingrowth into the scaffold and new bone formation inside the scaffold than the PLGA scaffold. It seems that 5% addition of PVA to PLGA to fabricate PLGA/PVA blend scaffolds is enough for improving the hydrophilicity and cell compatibility of the scaffolds.     

Molecular mechanism for loss of visual cortical responsiveness following brief monocular deprivation

A dramatic form of experience-dependent synaptic plasticity is revealed in visual cortex when one eye is temporarily deprived of vision during early postnatal life. Monocular deprivation (MD) alters synaptic transmission such that cortical neurons cease to respond to stimulation of the deprived eye, but how this occurs is poorly understood. Here we show in rat visual cortex that brief MD sets in motion the same molecular and functional changes as the experimental model of homosynaptic long-term depression (LTD), and that prior synaptic depression by MD occludes subsequent induction of LTD. The mechanisms of LTD, about which there is now a detailed understanding, therefore contribute to visual cortical plasticity.     

Analysis of children with type 1 diabetes in Korea: high prevalence of specific anti-islet autoantibodies, immunogenetic similarities to Western populations with "unique" haplotypes, and lack of discrimination by aspartic acid at position 57 of DQB

This study analyzed the expression of anti-islet autoantibodies and HLA-DR and -DQ genotypes in Korean children with type 1 diabetes mellitus (T1DM). The positivity of the anti-ICA512, anti-GAD65, and anti-insulin autoantibodies in the newly onset T1DM patients (n = 15) was 66.7%, 86.7%, and 46.7%, respectively, and all of them had one or more of the autoantibodies. HLA analysis showed higher frequencies of HLA-DRB1*0301, *0405, *09012 and -DQB1*0201, *0401, *03032 alleles in T1DM patients compared to controls (P(c) < 0.05). Because HLA-DQB1*0401, *03032 alleles carry aspartic acid at position 57 of DQB, susceptibility to T1DM in Korean children was not related to the presence of aspartic acid at position 57 of DQB1 locus. We suggest this unique HLA-DR, -DQ allele distribution might be an important factor for the low incidence of T1DM in Korea, and the combined anti-islet autoantibody assays could be valuable screening markers for the early detection of T1DM in Korea.     

A case of maternal tetanus in Korea

Tetanus is uncommon in Korea due to the introduction of vaccination programs and advances in public health. A case of maternal tetanus occurred on the 9 day postpartum in a 29-yr-old woman, who had not received a 10-yr-booster of tetanus-diphtheria toxoid after receiving the primary series of tetanus-toxoid-containing vaccine. There has hitherto been no reports on maternal tetanus in Korea. This case illustrates that tetanus remains a medical problem, principally among non- and under-immunized adults. The only way to fully prevent this disease is to ensure adequate immunization in all adults.     

Debate on annual influenza vaccination in healthcare workers for the same subtype under the vaccine shortage.

BACKGROUND: Influenza vaccination is the primary method for preventing influenza and its severe complications. Healthcare workers (HCWs) are one of the priority groups for the influenza vaccination. OBJECTIVES: To determine whether healthy HCWs, who were vaccinated with the same subtype for the two previous years, could be given less priority for influenza immunization under the vaccine shortage. STUDY DESIGN: We measured hemagglutination-inhibition antibody titers from sequential serum samples in 50 pre-immune subjects and 50 age-matched vaccine-naive subjects: immediately prior to the administration of the vaccine, 4-6 weeks, and 6 months after the vaccination. RESULTS: Prevaccination titers were maintained above protective level and high protection rates were observed for all three strains in pre-immune subjects: A/H1N1, A/H3N2, and B strains. As for the sequential changes, the protection rates for all three strains still remained above 70% until 6 months following the vaccination. CONCLUSION: Skipping influenza vaccination for a year could be considered in healthy pre-immune HCWs under the epidemic of the same subtype as two previous years.     

Contrast sensitivity function of sound eye after occlusion therapy in the amblyopic children

To verify the changes of mesopic and photopic contrast sensitivity function of sound eye whose visual acuity was kept the same after occlusion therapy in the amblyopic children. Fourteen sound eyes of amblyopic children (mean; 7.67 years; S.D., 1.50 years) who kept their visual acuity the same after the occlusion therapy were tested. The children had 6 hours of part-time patch therapy for 3 months prior to this examination. Among 14 amblyopic children, 8 were anisometric and 6 were strabismic amblyopes. Using the visual capacity analyzer which measures the minimal contrast level at from low to high spatial frequencies, the contrast sensitivity of sound eye was measured, under both photopic and mesopic condition, before and after 3 months of occlusion therapy. Comparing the contrast sensitivity of sound eye after the occlusion therapy to that before the occlusion, there was no statistical difference in photopic condition. When it comes to mesopic condition, the contrast sensitivity decreased at the intermediate spatial frequency level (3-13 c.p.d, p=0.028) after the occlusion therapy. The occlusion caused statistically significant decrease in mesopic contrast sensitivity, when the visual acuity was not changed after the occlusion therapy. It may indicate that mesopic contrast sensitivity can be considered as a useful tool for early detection of hidden occlusion amblyopia.     

Receptors for Treponema pallidum attachment to the surface and matrix proteins of cultured human dermal microvascular endothelial cells

Pathogenicity of Treponema pallidum may depend upon the binding of Treponema pallidum to matrix proteins, especially to fibronectin. Infectious organism or cell to matrix interactions are mediated by a family of adhesion molecule receptors known as integrins. Once in the host, the pathogenic Treponema pallidumdum adheres to the vascular endothelium and readily penetrates surrounding tissues. Fibronectin plays an important role in the mediation of the attachment of Treponema pallidum to host cells, including endothelial cells. We found that the binding of Treponema pallidum to human dermal microvascular endothelial cells and to a glass surface coated with fibronectin is inhibited by the presence of arginine-glycine- aspartic acid (RGD), and analysis of the surface receptor revealed an antigenic similarity to an integrin molecule, namely alpha5. This ability to adhere to host endothelium and fibronectin is quite unique to T. pallidum among the treponemes, and may be a key pathogenic factor.     

PD-1-Expressing SARS-CoV-2-Specific CD8+ T Cells Are Not Exhausted,but Functional in Patients with COVID-19

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Bronchoalveolar lavage cytokine profiles in acute asthma and acute bronchiolitis

BACKGROUND: The pathogenetic basis for the relationship between acute bronchiolitis and asthma has not yet been completely elucidated. OBJECTIVE: The aim of this study was to compare these 2 diseases in terms of their patterns of airway cytokine response (T(H)1 or T(H)2). METHODS: By using a bronchoalveolar lavage (BAL) technique, this study investigated the cytokine levels of BAL fluid in children with acute asthma who had no identifiable respiratory syncytial virus (RSV) infection (n = 18) and in infants with acute bronchiolitis caused by RSV (n = 22). Comparisons were made with normal control subjects (n = 14). IFN-gamma (T(H)1) and IL-4 and IL-5 (T(H)2) levels were measured in concentrated BAL fluids by means of ELISA. RESULTS: The IL-5 level (P <.001) and IL-5/IFN-gamma ratio (P <.001) were significantly increased in the asthmatic group with no identifiable RSV infection and in the RSV-induced bronchiolitis group compared with values in the control group. When infants in the bronchiolitis group were divided into eosinophil-positive and eosinophil-negative subgroups, the eosinophil-positive subgroup had significantly increased IL-5 levels (P <.001) and IL-5/IFN-gamma ratios (P <.01) compared with those in the control group, but similar cytokine responses were not induced in the eosinophil-negative subgroup. The percentage of BAL eosinophils correlated significantly with levels of BAL IL-5 in both the asthma group (r = 0.80, P =.000) and the bronchiolitis group (r = 0.82, P =.000). CONCLUSIONS: These findings suggest that a subgroup of the RSV-induced bronchiolitis group results in a T(H)2-type response, and this could provide a valuable framework to explain the link between RSV-induced bronchiolitis and asthma.