Cultivation of auricular chondrocytes in poly(ethylene glycol)/poly(ε-caprolactone) hydrogel for tracheal cartilage tissue engineering in a rabbit model.

Tissue engineering has the potential to overcome the limitations of tracheal reconstruction. To tissue-engineer a tracheal cartilage, auricular chondrocytes were encapsulated in a photocurable poly(ethylene glycol)/poly(ε-caprolactone) (PEG/PCL) hydrogel. Chondrogenic genes, including Sox9, Acan and Col2a1, were up-regulated in auricular chondrocytes after 2 weeks of in vitro cultivation in the PEG/PCL hydrogel. Co-cultivation of 70 % auricular chondrocytes and 30 % bone marrow mesenchymal stem cells (BMSCs) accelerated the chondrogenic genes' expression in the PEG/PCL hydrogel. Cartilaginous matrix markers, including proteoglycans and collagen type II, were detected in the chondrocytes-encapsulated PEG/PCL hydrogel after 4 weeks of in vitro cultivation. The higher expression level of cartilaginous matrix markers was observed in the PEG/PCL hydrogel with co-cultivation of 70 % chondrocytes and 30 % BMSCs. After 4 weeks of ectopic cultivation in rabbits, the cylindrical PEG/PCL structure was sustained with the use of a luminal silicon stent. However, without the stent, the construct collapsed under a compression force. No fibrosis or vessel ingrowth were found in the PEG/PCL hydrogel after 4 weeks of ectopic cultivation, whereas the auricular chondrocytes showed proteoglycans' accumulation and collagen type II production. Rabbit auricular chondrocytes could survive and retain chondrogenic ability in the PEG/PCL hydrogel under both in vitro and in vivo conditions. While the PEG/PCL hydrogel did not show sufficient mechanical properties for supporting the cylindrical shape of the construct, the high chondrogenesis level of chondrocytes in the PEG/PCL hydrogel displayed the potential of this material for tracheal tissue engineering.

Gonorrhea infection increases the risk of prostate cancer in Asian population: a nationwide population-based cohort study.

This nationwide population-based retrospective cohort study evaluated the risk of developing prostate cancer among patients with gonorrhea. We identified cases of newly diagnosed gonorrhea in men between 2000 and 2010 from the Taiwan National Health Insurance Research Database. Each patient with gonorrhea was matched to four controls, based on age and index year. All subjects were followed up from the index date to December 31, 2010. The Cox proportional hazards regression model was used to assess the risk of prostate cancer. A total of 355 men were included in the study group, and 1,420 age-matched subjects without gonorrhea were included in the control group. After adjusting for age, comorbidities, urbanization level, hospital level, and monthly income, gonorrhea was significantly associated with an increased risk of prostate cancer (adjusted hazard ratio = 5.66, 95% confidence interval = 1.36-23.52). Men aged 45-70 years and those with lower monthly income were more strongly associated with prostate cancer in the study group than the control group. The higher risk for developing prostate cancer were also found in those without syphilis, without genital warts, without diabetes mellitus, without chronic obstructive pulmonary disease, without benign prostatic hypertrophy, without chronic prostatitis, and without alcoholism. The Kaplan-Meier analysis showed the risk of prostate cancer was significantly higher in the study group than in the control group. Gonorrhea may be involved in the development of prostate cancer. More intensive screening and prevention interventions for prostate cancer should be recommended in men with gonorrhea.

Monthly recurrent herpes simplex virus blepharitis in a boy for more than 10 years.

Ocular herpes simplex virus (HSV) infection is generally accepted to be a unilateral disease and simultaneous bilateral recurrent ocular HSV disease is uncommon. Recurrent ocular herpes was generally thought to be characterized by corneal involvement. We here report an 11-year-old boy with monthly bilateral recurrent HSV type 1 blepharitis for more than 10 years. He had a general normal immunological examination. Only supportive or topical acyclovir ointment treatment proved adequate for controlling the monthly recurrent disease without corneal involvement or other sequelae to date. The case highlights the unusual presentation, general normal immune function, clinical course and treatment opinion for recurrent HSV blepharitis.

Use of a new fluorescence immunoassay to detect anti-dsDNA antibodies is more correlated with disease activity and complement than the ELISA method in SLE patients.

To determine whether the serum levels of anti-double strand DNA (anti-dsDNA) autoantibodies detected using a newly developed fluorescence immunoassay (FIA) in patients with systemic lupus erythematosus (SLE) correlated more with clinical parameters, such as SLE disease activity index (SLEDAI), complement and the occurrence of nephritis when compared with traditional enzyme-linked immunosorbent assay (ELISA), we prospectively collected 124 serum samples from 31 patients who had juvenile-onset SLE and were regularly monitored every 2 months at our outpatient clinic. At every visit, clinical manifestations and laboratory parameters were assessed and the SLEDAI was determined. Correlation analyses between the two different measurements of anti-dsDNA antibodies and SLEDAI, serum complement levels and the occurrence of nephritis were performed. The results showed that anti-dsDNA autoantibodies detected using both ELISA and FIA significantly correlated with SLEDAI, and significantly and inversely correlated with the serum levels of C3 and C4. FIA had significantly higher correlation with SLEDAI and C4 than did ELISA. The mean values of anti-dsDNA antibodies detected using FIA in patients with nephritis were significantly higher than in those without nephritis. In contrast, the values of anti-dsDNA antibodies detected using ELISA did not show significant differences between these two groups. We conclude that FIA had better correlation with SLEDAI, C4 and the occurrence of nephritis, and comparable correlations with C3 that were similar to the results found using ELISA. Thus, it is worthwhile developing the FIA method for clinical evaluation of disease activity in SLE patients.

Comparison of soluble adhesion molecules in juvenile idiopathic arthritis between the active and remission stages.

OBJECTIVE: To determine the serum levels of soluble adhesion molecules in patients with juvenile idiopathic arthritis (JIA), and to determine whether the levels of these molecules differ between active disease and remission in the same JIA subtype, and whether differences in these levels exist between controls and the three JIA subtypes. METHODS: The serum levels of soluble E-selectin (sE-selectin) and soluble intercellular adhesion molecule-1 (sICAM-1) were determined by enzyme linked immunosorbent assay (ELISA) in 40 patients with JIA (12 systemic, 13 polyarticular, and 15 oligoarticular) who had active disease or were in clinical remission and 16 healthy controls. Differences in the levels of adhesion molecules of the same JIA subtype during different disease activity were determined by the paired t test, and differences between the disease and control groups were calculated by one way analysis of variance. A value p<0.01 was considered significant. RESULTS: During the same disease stage (active or in remission), systemic JIA was associated with a significantly higher sE-selectin level than the oligoarticular JIA subtype, whereas this was not found for sICAM-1. Although the mean levels of sE-selectin and sICAM-1 in active systemic and polyarticular JIA were higher than those in remission, this did not reach statistical significance. The levels of sE-selectin and sICAM-1 of the three JIA subtypes, in both the active stage and clinical remission, were still significantly higher than in normal controls. CONCLUSIONS: Systemic JIA is associated with a higher sE-selectin level than oligoarticular JIA both in active disease and in clinical remission. This may explain why the morbidity of systemic JIA is greater than that of oligoarticular JIA-namely, owing to increased endothelial cell activation. As significantly higher levels of sE-selectin and sICAM-1 were found in the active and remission stages of the three JIA subtypes compared with those in the control group, JIA may recur even when clinical remission has been achieved.

Salicylates inhibit flavivirus replication independently of blocking nuclear factor kappa B activation.

Flaviviruses comprise a positive-sense RNA genome that replicates exclusively in the cytoplasm of infected cells. Whether flaviviruses require an activated nuclear factor(s) to complete their life cycle and trigger apoptosis in infected cells remains elusive. Flavivirus infections quickly activate nuclear factor kappa B (NF-kappaB), and salicylates have been shown to inhibit NF-kappaB activation. In this study, we investigated whether salicylates suppress flavivirus replication and virus-induced apoptosis in cultured cells. In a dose-dependent inhibition, we found salicylates within a range of 1 to 5 mM not only restricted flavivirus replication but also abrogated flavivirus-triggered apoptosis. However, flavivirus replication was not affected by a specific NF-kappaB peptide inhibitor, SN50, and a proteosome inhibitor, lactacystin. Flaviviruses also replicated and triggered apoptosis in cells stably expressing IkappaBalpha-DeltaN, a dominant-negative mutant that antagonizes NF-kappaB activation, as readily as in wild-type BHK-21 cells, suggesting that NF-kappaB activation is not essential for either flavivirus replication or flavivirus-induced apoptosis. Salicylates still diminished flavivirus replication and blocked apoptosis in the same IkappaBalpha-DeltaN cells. This inhibition of flaviviruses by salicylates could be partially reversed by a specific p38 mitogen-activated protein (MAP) kinase inhibitor, SB203580. Together, these results show that the mechanism by which salicylates suppress flavivirus infection may involve p38 MAP kinase activity but is independent of blocking the NF-kappaB pathway.

The effect of human bcl-2 and bcl-X genes on dengue virus-induced apoptosis in cultured cells.

Infection of dengue viruses (DENs) can cause human dengue fever, hemorrhagic fever, or shock syndrome. Although DEN-induced apoptosis has been implicated in pathogenesis of the DEN-related diseases, the underlying mechanism remains largely unexplored. In this study, we investigated the effect of ectopic expression of human bcl-2 and bcl-X genes on DEN-induced apoptosis in cultured cells. We employed a human isolate of DEN serotype 2 (DEN-2), PL046, which not only caused cell-cycle arrest in the G1 phase but also induced apoptosis in infected baby hamster kidney (BHK-21) cells, murine neuroblastoma N18 cells, and human neuronal NT-2 cells. Our results reveal that overexpression of bcl-2 in fibroblast-like BHK-21 cells, although not inhibiting virus yields, delayed the process of DEN-induced apoptosis, thereby permitting surviving cells to become persistently infected. In contrast, stable bcl-2 expression in neuronal N18 cells failed to block DEN-induced apoptosis. On the other hand, Bcl-X(L), expressed predominantly in the nervous system, appeared to delay DEN's killing effect in neuronal N18 cells but not in fibroblast-like BHK-21 cells. In addition, inducible expression bcl-X(s), despite its proapoptotic property in other reported system, was found to merely accelerate cell death in DEN-infected N18 but not in infected BHK-21 cells. Thus, through studying the effect of human bcl-2-related genes, our results suggest that DEN infection may trigger target cells to undergo morphologically similar but biochemically distinct apoptotic pathways in a cell-specific manner.

Membrane permeabilization by small hydrophobic nonstructural proteins of Japanese encephalitis virus.

Infection with Japanese encephalitis virus (JEV), a mosquito-borne flavivirus, may cause acute encephalitis in humans and induce severe cytopathic effects in various types of cultured cells. We observed that JEV replication rendered infected baby hamster kidney (BHK-21) cells sensitive to the translational inhibitor hygromycin B or alpha-sarcine, to which mock-infected cells were insensitive. However, little is known about whether any JEV nonstructural (NS) proteins contribute to virus-induced changes in membrane permeability. Using an inducible Escherichia coli system, we investigated which parts of JEV NS1 to NS4 are capable of modifying membrane penetrability. We found that overexpression of NS2B-NS3, the JEV protease, permeabilized bacterial cells to hygromycin B whereas NS1 expression failed to do so. When expressed separately, NS2B alone, but not NS3, was sufficient to alter bacterial membrane permeability. Similarly, expression of NS4A or NS4B also rendered bacteria susceptible to hygromycin B inhibition. Examination of the effect of NS1 to NS4 expression on bacterial growth rate showed that NS2B exhibited the greatest inhibitory capability, followed by a modest repression from NS2A and NS4A, whereas NS1, NS3, and NS4B had only trivial influence with respect to the vector control. Furthermore, when cotransfected with a reporter gene luciferase or beta-galactosidase, transient expression of NS2A, NS2B, and NS4B markedly reduced the reporter activity in BHK-21 cells. Together, our results suggest that upon JEV infection, these four small hydrophobic NS proteins have various modification effects on host cell membrane permeability, thereby contributing in part to virus-induced cytopathic effects in infected cells.

Calculations of depth-dose distributions, cross sections and momentum loss.

The ability to know with precision the depth-dose, dose average LET, fluence and energy distributions is of great importance in many research fields, including therapeutic and diagnostic medicine when using heavy ion beams, as well as in space research. We have therefore developed a model and a computer code for calculating these distributions when using high energy proton or heavy ion beams. In this model, we use semi-empirical total reaction and partial cross section formulas developed by us and a new prescription to take into account the energy and momentum loss of the secondary nuclei. In this paper, we will also present an empirical equation for the total inelastic 4He-p cross section, as well as the partial cross sections for the production of 3He, 3H, 2H, p and n.

Spallation processes and nuclear interaction products of cosmic rays.

Most cosmic-ray nuclei heavier than helium have suffered nuclear collisions in the interstellar gas, with transformation of nuclear composition. The isotopic and elemental composition at the sources has to be inferred from the observed composition near the Earth. The source composition permits tests of current ideas on sites of origin, nucleosynthesis in stars, evolution of stars, the mixing and composition of the interstellar medium and injection processes prior to acceleration. The effects of nuclear spallation, production of radioactive nuclides and the time dependence of their decay provide valuable information on the acceleration and propagation of cosmic rays, their nuclear transformations, and their confinement time in the Galaxy. The formation of spallation products that only decay by electron capture and are relatively long-lived permits an investigation of the nature and density fluctuations (like clouds) of the interstellar medium. Since nuclear collisions yield positrons, antiprotons, gamma rays and neutrinos, we shall discuss these topics briefly.

Model analysis of Space Shuttle dosimetry data.

An extensive model analysis of plastic track detector measurements of high-LET particles on the Space Shuttle has been performed. Three shuttle flights: STS-51F (low-altitude, high-inclination), STS-51J (high-altitude, low-inclination), and STS-61C (low-altitude, low-inclination) are considered. The model includes contributions from trapped protons and galactic cosmic radiation, as well as target secondary particles. Target secondaries, expected to be of importance in thickly shielded space environments, are found to be a significant component of the measured LET (linear energy transfer) spectra.

Radiation hazards on space missions outside the magnetosphere.

Future space missions outside the magnetosphere will subject astronauts to a hostile and unfamiliar radiation environment. An annual dose equivalent to the blood-forming organs (BFOs) of approximately 0.5 Sv is expected, mostly from heavy ions in the galactic cosmic radiation. On long-duration missions, an anomalously-large solar energetic particle event may occur. Such an event can expose astronauts to up to approximately 25 Gy (skin dose) and up to approximately 2 Sv (BFO dose) with no shielding. The anticipated radiation exposure may necessitate spacecraft design concessions and some restriction of mission activities. In this paper we discuss our model calculations of radiation doses in several exo-magnetospheric environments. Specific radiation shielding strategies are discussed. A new calculation of aluminum equivalents of potential spacecraft shielding materials demonstrates the importance of low-atomic-mass species for protection from galactic cosmic radiation.

A comparison of neutron-induced SEU rates in Si and GaAs devices.

The single-event-upset rates due to neutron-induced nuclear recoils have been calculated for Si and GaAs components using the HETC and MCNP codes and the ENDF data base for (n, p) and (n, alpha) reactions. For the same critical charge and sensitive volume, the upset rate in Si exceeds that of GaAs by a factor of about 1.7, mainly because more energy is transferred in neutron interactions with lighter Si nuclei. The upset rates due to neutrons are presented as functions of critical charge and atmospheric altitude. Upsets induced by cosmic-ray nuclei, secondary protons and neutrons are compared.

Transport of cosmic ray nuclei in various materials.

NASA: Cosmic-ray heavy ions have become a concern in space radiation effects analyses. Heavy ions rapidly deposit energy and create dense ionization trails as they traverse materials. Collection of the free charge disrupts the operation of microelectronic circuits. This effect, called the single-event upset, can cause a loss of digital data. Passage of high linear energy transfer particles through the eyes has been observed by Apollo astronauts. These heavy ions have great radiobiological effectiveness and are the primary risk factor for leukemia induction on a manned Mars mission. Models of the transport of heavy cosmic-ray nuclei through materials depend heavily on our understanding of the cosmic-ray environment, nuclear spallation cross sections, and computer transport codes. Our group has initiated and pursued the development of a full capability for modeling these transport processes. A recent review of this ongoing effort is presented in Ref. 5. In this paper, we discuss transport methods and present new results comparing the attenuation of cosmic rays in various materials.^ieng

Distributed reacceleration of cosmic rays.

We develop a model in which cosmic rays, in addition to their initial acceleration by a strong shock, are continuously reaccelerated (e.g., by weak shocks) while propagating through the galaxy. The equations describing this acceleration scheme are solved analytically (approximating ionization losses by a cutoff) and numerically. Solutions for the spectra of primary and secondary cosmic rays are given in a closed analytic form, and they allow a rapid search in parameter space for viable propagation models with distributed reacceleration included. The observed boron-to-carbon ratio can be reproduced by the reacceleration theory over a range of escape parameters, some of them quite different from the standard "leaky box" model. It is also shown that even a very modest amount of reacceleration by strong shocks causes the boron-to carbon ratio to level off at sufficiently high energies, and this effect may be observed in the CRNE data. Several other curiosities in the data may be explained naturally if a modest amount of distributed reacceleration is invoked, including (a) the apparent truncation at low energy in the otherwise exponential pathlength distribution associated with the leaky box model, (b) the sub-iron isotopic anomalies and other effects noted by Silberberg et al., and (c) the discrepancy between the reported 10Be lifetime and the lifetime of cosmic rays in the dense strata of the galactic disk.

Radiation doses and LET distributions of cosmic rays.

Among cosmic rays, the heavy nuclei ( HZE particles) like iron provide the dominant contribution to the dose equivalent during exposures in space. The LET distributions and radiation doses of cosmic-ray components have been calculated--with and without the quality factors--for a set of shielding and tissue self-shielding penetration depths. The relative contributions of heavy ions among solar flare particles to the dose equivalent are also explored. The transport calculations of the nuclei in air, shielding materials, and biological tissue-like material were carried out using the partial and total nuclear cross-section equations and nuclear propagation codes of Silberberg and Tsao . Outside the magnetosphere , at solar minimum, the product of the unshielded dose and the quality factors of cosmic-ray protons and heavy nuclei with atomic number Z greater than or equal to 6 are about 5 and 47 rem/year, respectively. With 4 g/cm2 aluminum shielding and at a depth of 5 cm in a biological phantom of 30 cm diameter, the respective values of the dose equivalents are about 4 and 11 rem/year. Due to the hard spectrum of cosmic rays, the attenuation of protons thus is relatively modest, while that of heavy nuclei is larger due to the larger interaction cross section. The dose equivalent of neutrons in the shielded case mentioned above is similar to that of protons. The biological risks are tentatively assessed in terms of the BEIR 1980 report. Uncertainties in risks due to possible large RBE values at low doses of high-LET radiation and due to the microbeam nature of damage by heavy ions are pointed out. Certain experiments and studies by radiobiologists are suggested for reducing the uncertainties in the estimates of the risks.

LET-distributions and doses of HZE radiation components at near-Earth orbits.

Among cosmic rays, the heavy nuclei ranging from carbon to iron provide the principal contribution to the dose equivalent. The LET-distributions and absorbed dose aid dose equivalent have been calculated and are presented as a function of shielding and tissue self-shielding. At solar minimum, outside the magnetosphere, the unshielded dose equivalent of nuclei with atomic number Z > or = 6 is about 47 rem/year. The contribution of the target nuclei adds 7 rem/year. With 4 g/cm2 aluminum shielding, and at a depth of 5 cm in a biological phantom of 30 cm diameter, the respective values are 11 and 10 rem/year. Corresponding dose rates for orbits with various inclinations are presented, as well as the LET distributions of various components of cosmic rays.