Function of T regulatory type 1 cells is down-regulated and is associated with the clinical presentation of coronary artery disease

T regulatory type 1 (Tr1) cells can promote tolerance and suppress inflammation. Atherosclerosis may be induced by the proinflammatory activation of cells in the vasculature and the immune system. Hence, we wondered whether defects in Tr1 function were a contributing factor to coronary artery disease (CAD). Data showed that the frequency of IL-10⁺ Tr1 cells was significantly lower in CAD patients than in controls. Compared to healthy controls, Tr1 cells from CAD patients presented lower CTLA-4 but higher PD-1 expression, in addition to lower IL-10 secretion. When co-incubated with Tconv cells, the CD4⁺CD49b⁺LAG-3⁺CD45RO⁺ Tr1 cells presented IL-10-dependent inhibitory effects, and those from CAD patients presented significantly lower suppression capacity than those from healthy controls. Interestingly, the characteristics of Tr1 cells were associated with clinical features of CAD patients. The frequency of Tr1 cells and the IL-10 and LAG-3 expression by Tr1 cells were negatively correlated with the BMI of the CAD patients. In addition, the Tr1 frequency and the LAG-3 and CTLA-4 expression on Tr1 cells were lower in CAD patients with higher numbers of narrowed vessels. Together, these results suggest that in CAD, Tr1 cells present multiple defects, which are associated with the clinical presentation of the disease.     

Automatic Organ Segmentation for CT Scans Based on Super-Pixel and Convolutional Neural Networks

Accurate segmentation of specific organ from computed tomography (CT) scans is a basic and crucial task for accurate diagnosis and treatment. To avoid time-consuming manual optimization and to help physicians distinguish diseases, an automatic organ segmentation framework is presented. The framework utilized convolution neural networks (CNN) to classify pixels. To reduce the redundant inputs, the simple linear iterative clustering (SLIC) of super-pixels and the support vector machine (SVM) classifier are introduced. To establish the perfect boundary of organs in one-pixel-level, the pixels need to be classified step-by-step. First, the SLIC is used to cut an image into grids and extract respective digital signatures. Next, the signature is classified by the SVM, and the rough edges are acquired. Finally, a precise boundary is obtained by the CNN, which is based on patches around each pixel-point. The framework is applied to abdominal CT scans of livers and high-resolution computed tomography (HRCT) scans of lungs. The experimental CT scans are derived from two public datasets (Sliver 07 and a Chinese local dataset). Experimental results show that the proposed method can precisely and efficiently detect the organs. This method consumes 38 s/slice for liver segmentation. The Dice coefficient of the liver segmentation results reaches to 97.43%. For lung segmentation, the Dice coefficient is 97.93%. This finding demonstrates that the proposed framework is a favorable method for lung segmentation of HRCT scans.     

Light-driven generation of hydrogen: New chromophore dyads for increased activity based on Bodipy dye and Pt(diimine)(dithiolate) complexes

New dyads consisting of a strongly absorbing Bodipy (dipyrromethene-BF₂) dye and a platinum diimine dithiolate (PtN₂S₂) charge transfer (CT) chromophore have been synthesized and studied in the context of the light-driven generation of H₂ from aqueous protons. In these dyads, the Bodipy dye is bonded directly to the benzenedithiolate ligand of the PtN₂S₂ CT chromophore. Each of the new dyads contains either a bipyridine (bpy) or phenanthroline (phen) diimine with an attached functional group that is used for binding directly to TiO₂ nanoparticles, allowing rapid electron photoinjection into the semiconductor. The absorption spectra and cyclic voltammograms of the dyads show that the spectroscopic and electrochemical properties of the dyads are the sum of the individual chromophores (Bodipy and the PtN₂S₂ moieties), indicating little electronic coupling between them. Connection to TiO₂ nanoparticles is carried out by sonication leading to in situ attachment to TiO₂ without prior hydrolysis of the ester linking groups to acids. For H₂ generation studies, the TiO₂ particles are platinized (Pt-TiO₂) so that the light absorber (the dyad), the electron conduit (TiO₂), and the catalyst (attached colloidal Pt) are fully integrated. It is found that upon 530 nm irradiation in a H₂O solution (pH 4) with ascorbic acid as an electron donor, the dyad linked to Pt-TiO₂ via a phosphonate or carboxylate attachment shows excellent light-driven H₂ production with substantial longevity, in which one particular dyad [4(bpyP)] exhibits the highest activity, generating ∼40,000 turnover numbers of H₂ over 12 d (with respect to dye).Water splitting into hydrogen and oxygen is the key energy-storing reaction of artificial photosynthesis (AP) and one of the most promising long-term strategies for carbon-free energy on a potentially global scale (1). As a redox reaction, water splitting has been studied primarily in terms of its two half-reactions, the reduction of aqueous protons to H₂ and the oxidation of water to O₂ (2–13). Whereas some of these studies date back more than 30 y (14–22), recent progress on each half-reaction has been notable, particularly with regard to catalyst development and mechanistic understanding of each transformation (6, 23–29). In this paper, we focus on efforts dealing with the light-driven generation of H₂, which in its simplest form requires a light absorber or photosensitizer (PS) for electron-hole creation, a means or pathway for charge separation and electron transfer, an aqueous proton source, a catalyst for collecting electrons and protons and promoting their conversion to H₂, and an ultimate source of electrons in the form of an electron donor.Dating from the earliest work on the light-driven generation of H₂, the photosensitizer has most often been a Ru(II) complex with 2,2′-bipyridine (bpy) and/or related heterocyclic ligands having a long-lived triplet metal-to-ligand charge transfer state (³MLCT) (5, 7, 30–33). Recent studies have included analogous Ir(III) d⁶ systems based on phenylpyridine (ppy) ligands in place of bpy (34). With charge transfer excited states, the sensitizers are poised for photoinduced electron transfer following photon absorption and intersystem crossing (ISC). Another set of charge-transfer chromophores that have been used in related systems is [Pt(terpyridyl)(arylacetylide)]⁺ complexes that also have ³MLCT states (35–37). Despite their success with photoinduced electron transfer, all of these charge transfer (CT) complexes have absorptions that are too weak for efficient photon capture with molar extinction coefficients (ε) of 7–15 × 10³ M⁻¹⋅cm⁻¹, and the energies of their singlet absorbing states (¹MLCT) are too high (typically >2.6 eV with λ < 490 nm) for effective use of the solar spectrum. More strongly absorbing organic dyes with ε of ∼10⁵ M⁻¹⋅cm⁻¹ were also examined during early studies of the light-driven generation of H₂. Whereas those with heavier halogen substituents such as Rose Bengal and Eosin Y were found to promote H₂ formation because of facile ISC to long-lived ³ππ* states, they also exhibited poor photostability, decomposing within 3–5 h (38–41).Platinum diimine dithiolate complexes (PtN₂S₂) such as 1 constitute another class of charge transfer chromophores that are solution luminescent and undergo electron transfer quenching of both oxidative and reductive types (42–48). The excited state energies of these complexes are significantly lower than those of the Ru(bpy), Ir(ppy), and Pt(terpyridyl) complexes mentioned above and have an excited state that has been described as having both MLCT and ligand-to-ligand charge transfer (LLCT) character. In complexes such as 1, the highest occupied molecular orbital (HOMO) is of mixed character, being composed of substantial percentages of both Pt-based and dithiolate-based wavefunctions. As a consequence of the mixed character of the HOMO in PtN₂S₂, the excited states derived from HOMO to LUMO (lowest unoccupied molecular orbital) excitation have been labeled mixed-metal ligand-to-ligand′ charge transfers (MMLL′CT). Based on these charge transfer states, two of the PtN₂S₂ complexes, including 1 with R = COOH, were examined as photosensitizers for H₂ generation with TiO₂ as the electron conduit and Pt islands on the TiO₂ surface as the catalyst (49). The deprotonated carboxlyate groups of di(carboxy)bipyridine (dcbpy) served to link the PS to the platinized TiO₂ (Pt-TiO₂). The system produced hydrogen and proved to be stable for more than 70 h, using light of λ > 450 nm. However, activity of the system was low, based in part on the low absorptivity of the PtN₂S₂ chromophore and the small amount of the complex bound to TiO₂.To improve absorptivity of the PS in such H₂ generating systems, an approach was initiated in which a strongly absorbing organic dye was linked directly to the PtN₂S₂ moiety for more efficient photon absorption and subsequent energy transfer to the CT chromophore. Such a strategy had been adopted by Ziessel through the synthesis of a bipyridine linked to a dipyrromethene-BF₂ (Bodipy) dye similar to 2 and was examined for Ru complexes containing this ligand, resulting in sensitization of the lower-energy ³ππ* of the Bodipy part of the molecule (50). In a study by Lazarides et al. (51), the dye-CT dyad 3 that contained 2 and the dithiolate-linked Bodipy dyad 4 were synthesized and examined by absorption spectroscopy and transient absorption measurements to determine the potential success of photoinduced charge separation. In that study, it was determined that the absorption spectra of the two dyads are essentially the sum of each constituent chromophore and that the redox potentials of each component are virtually unaffected by bringing the two units together in a dyad. The measurements also showed that energy transfer from the ¹ππ* state of the Bodipy moiety to the ¹MMLL′CT state was energetically favorable and that for both 3 and 4, the dynamics progressed as shown in Scheme 1. Although the rates of both singlet energy transfer (SenT) and ISC for the two dyads were similar and proceeded in less than 1 ps, a significant difference was seen for the triplet energy transfer (TEnT) step with the time constant for 3 being 8 ps whereas that for 4 was 160 ps, indicating that for productive electron transfer to TiO₂, the arrangement in 4 with Bodipy attached to the dithiolate was preferred.Open in a separate windowScheme 1.Jablonski diagram of the Bodipy-PtN₂S₂ dyads showing the transitions between the different states (SEnT, singlet energy transfer; ISC, intersystem crossing; TEnT, triplet energy transfer).In this paper, the synthesis and characterization of dyads 4 with R = COOMe, P(O)(OEt)₂, CH₂(P(O)(OEt)₂) and an analogous phenanthroline (phenP) derivative 5 are described, along with studies of their ability to promote light-driven production of H₂ from aqueous protons in conjunction with Pt-TiO₂ as both electron conduit and catalyst. The benefit of attaching the strongly absorbing bodipy chromophore to the charge transfer PtN₂S₂ complex is discussed.     

Chronic Dietary Exposure to Aristolochic Acid and Kidney Function in Native Farmers from a Croatian Endemic Area and Bosnian Immigrants

Background and objectives

Improvements in agricultural practices in Croatia have reduced exposure to consumption of aristolochic acid-contaminated flour and development of endemic (Balkan) nephropathy. Therefore, it was hypothesized that Bosnian immigrants who settled in an endemic area in Croatia 15–30 years ago would be at lower risk of developing endemic nephropathy because of reduced exposure to aristolochic acid. To test this hypothesis, past and present exposure to aristolochic acid, proximal tubule damage as a hallmark of endemic nephropathy, and prevalence of CKD in Bosnian immigrants were analyzed.

Design, setting, participants, & measurements

In this cross-sectional observational study from 2005 to 2010, 2161 farmers were divided into groups: indigenous inhabitants from endemic nephropathy and nonendemic nephropathy villages and Bosnian immigrants; α-1 microglobulin-to-creatinine ratio >31.5 mg/g and eGFR<60 ml/min per 1.73 m² were considered to be abnormal.

Results

CKD and proximal tubule damage prevalence was significantly lower in Bosnian immigrants than inhabitants of endemic nephropathy villages (6.9% versus 16.6%; P<0.001; 1.3% versus 7.3%; P=0.003, respectively); 20 years ago, Bosnian immigrants observed fewer Aristolochia clematitis in cultivated fields (41.9% versus 67.8%) and fewer seeds among wheat seeds (6.1% versus 35.6%) and ate more purchased than homemade bread compared with Croatian farmers from endemic nephropathy villages (38.5% versus 14.8%, P<0.001). Both Croatian farmers and Bosnian immigrants observe significantly fewer Aristolochia plants growing in their fields compared with 15–30 years ago. Prior aristolochic acid exposure was associated with proximal tubule damage (odds ratio, 1.64; 95% confidence interval, 1.04 to 2.58; P=0.02), whereas present exposure was not (odds ratio, 1.31; 95% confidence interval, 0.75 to 2.30; P=0.33). Furthermore, immigrant status was an independent negative predictor of proximal tubule damage (odds ratio, 0.40; 95% confidence interval, 0.19 to 0.86; P=0.02).

Conclusions

Bosnian immigrants and autochthonous Croats residing in endemic areas are exposed significantly less to ingestion of aristolochic acid than in the past. The prevalence of endemic nephropathy and its associated urothelial cancers is predicted to decrease over time.     

Does Microwave Ablation of the Tumor Edge Allow for Joint-sparing Surgery in Patients With Osteosarcoma of the Proximal Tibia?

Background

Joint-sparing surgery of a patient’s native joint for osteosarcoma likely affords better function and comparable survival. However, it sometimes is challenging to resect a juxtaarticular osteosarcoma in a way that preserves the affected epiphysis because wide margins are necessary to minimize the risk of local recurrence. If there was a method to resect a tumor close to the joint and treat a potentially positive margin to prevent recurrence, it might allow salvage of a joint that otherwise might be lost.

Questions/purposes

We therefore asked (1) whether joint-preserving tumor resection could be performed for juxtaarticular osteosarcoma after microwave ablation of the tumor edge under navigation without leading to local recurrences, (2) what is the resulting function, and (3) what are the complications associated with this procedure.

Methods

Between 2009 and 2011, we treated 11 patients who had juxtaarticular osteosarcoma of the proximal tibia (mean age, 12 years; range, 9–16 years) with joint-preserving surgery by transepiphysis tumor resection after navigation-assisted microwave ablation of the tumor edge; they were followed a minimum of 37 months (mean, 48 months; range 37–62 months), and none was lost to followup. Patients were considered eligible for this procedure if they had a distance from the tumor edge to the articular surface between 10 to 15 mm, good chemotherapy responses, no pathologic fracture and no tumor involvement of major neurovascular structures. Allograft in combination with a vascularized fibula flap was used for segmental reconstruction. We recorded local tumor control, complications, and functional outcomes using the Musculoskeletal Tumor Society score, which ranges from 0 to 30, with higher scores indicating better function.

Results

There were no local recurrences. Major complications included osteonecrosis of part of the epiphysis in two patients and deep infection in one. The Musculoskeletal Tumor Society score ranged from 26 to 30 with a mean of 29.

Conclusions

In selected patients with osteosarcoma invading the epiphysis, navigated resection facilitates performing joint-sparing surgery, and in our small series, the adjuvant microwave ablation seemed to provide adequate local tumor control. Although more experience and longer followup are needed, this approach may make it possible to salvage more native joints when performing limb salvage for osteosarcoma.

Level of Evidence

Level IV, therapeutic study.     

Natural Polyphenols Enhance Stability of Crosslinked UHMWPE for Joint Implants

Background

Radiation-crosslinked UHMWPE has been used for joint implants since the 1990s. Postirradiation remelting enhances oxidative stability, but with some loss in strength and toughness. Vitamin E-stabilized crosslinked UHMWPE has shown improved strength and stability as compared with irradiated and remelted UHMWPE. With more active phenolic hydroxyl groups, natural polyphenols are widely used in the food and pharmaceutical industries as potent stabilizers and could be useful for oxidative stability in crosslinked UHMWPE.

Questions/purposes

We asked whether UHMWPE blended with polyphenols would (1) show higher oxidation resistance after radiation crosslinking; (2) preserve the mechanical properties of UHMWPE after accelerated aging; and (3) alter the wear resistance of radiation-crosslinked UHMWPE.

Methods

The polyphenols, gallic acid and dodecyl gallate, were blended with medical-grade UHMWPE followed by consolidation and electron beam irradiation at 100 kGy. Radiation-crosslinked virgin and vitamin E-blended UHMWPEs were used as reference materials. The UHMWPEs were aged at 120 °C in air with oxidation levels analyzed by infrared spectroscopy. Tensile (n = 5 per group) and impact (n = 3 per group) properties before and after aging as per ASTM F2003 were evaluated. The wear rates were examined by pin-on-disc testing (n = 3 per group). The data were reported as mean ± SDs. Statistical analysis was performed by using Student’s t-test for a two-tailed distribution with unequal variance for tensile and impact data obtained with n ≥ 3. A significant difference is defined with p < 0.05.

Results

The oxidation induction time of 100 kGy UHMWPE was prolonged to 144 hours with 0.05 wt% dodecyl gallate and 192 hours with 0.05 wt% gallic acid compared with 48 hours for 0.05 wt% vitamin E-blended UHMWPE. Accelerated aging of these polyphenol-blended UHMWPEs resulted in ultimate tensile strength of 50.4 ± 1.4 MPa and impact strength of 53 ± 5 kJ/m² for 100 kGy-irradiated UHMWPE with 0.05 wt% dodecyl gallate, for example, in comparison to 51.2 ± 0.7 MPa (p = 0.75) and 58 ± 5 kJ/m² (p = 0.29) before aging. The pin-on-disc wear rates of 100 kGy-irradiated UHMWPE with 0.05 wt% dodecyl gallate and 0.05 wt% gallic acid were 2.29 ± 0.31 and 1.65 ± 0.32 mg/million cycles, comparable to 1.68 ± 0.25 and 2.05 ± 0.22 mg/million cycles for 100 kGy-irradiated virgin and 0.05 wt% vitamin E-blended UHMWPE.

Conclusions

Based on the sample numbers tested in this study, polyphenols appear to effectively enhance the oxidation stability without altering the mechanical properties or pin-on-disc wear rate of radiation-crosslinked UHMWPE.

Clinical Relevance

Crosslinked UHMWPE with natural polyphenols with improved oxidative stability and low wear may find clinical application in joint implants.