Synthesis and Characterization of Benzodithiophene–Chalcogenophene Based Copolymers: A Comparative Study of Optoelectronic Properties and Photovoltaic Applications

Three copolymers based on poly(dialkoxybenzo[1,2‐b :4,5‐b′ ]dithiophene‐biselenophene) P3a and its heteroatom(s) analogues P3b and P3c are synthesized by Stille cross‐coupling to investigate the effects of the heteroatom on the optoelectronic and photovoltaic properties. Detailed characterizations of the copolymers are carried out by ¹H NMR, gel permeation chromatography, UV–vis absorption spectroscopy, and cyclic voltammetry. Optical absorption spectra reveal that the presence of biselenophene moiety in the copolymer P3a shows red‐shifted absorption (band gap 1.82 eV) compared to bithiophene containing copolymer P3b (band gap 1.91 eV), while band gap of bifuran containing copolymer P3c is 2.05 eV. The photovoltaic devices are fabricated using the copolymers P 3a – c blended with phenyl‐C₇₁‐butyric acid methyl ester as an acceptor material with the device structure of indium tin oxide (ITO)/MoO₃/active layer/Al. The power conversion efficiency is gradually increased with the replacement of furan by thiophene and furthermore thiophene by selenophene, respectively, due to increment in J _sc. Density functional theory calculations are studied on these three copolymers to understand the trends of energy levels and throughout compared with experimental data where applicable. The strategy has advantage of different aromaticities of heterocyclic rings combining with electronegativities and polarizabilities of the heteroatom(s) to allow the band gap engineering and tunability of photovoltaic performances.

     

Lumbar posterolateral fusion using heparin-conjugated fibrin for sustained delivery of bone morphogenic protein-2 in a rabbit model

We had devised a heparin-conjugated fibrin (HCF) system to deliver bone morphogenic proteins (BMPs) for a long-term period to enhance bone regeneration. In the present study, we tested the effectiveness of the delivery system for spinal fusion in a rabbit model. A total of 15 rabbits underwent posterolateral lumbar spine fusion with BMP-2 (50 μg per collagen sponge). The control group received only collagen sponges without BMP-2, another group (short-term delivery [SD] group) received collagen sponges filled with fibrin gel loaded with BMP-2, and the third group (long-term delivery [LD] group) received collagen sponges filled with HCF loaded with BMP-2. All animals were euthanized 8 weeks after surgery, and the fusion was assessed by radiographs, manual palpation, computed tomography, and mechanical testing. The fusion rate was significantly higher in the LD group using HCF than in the SD group or in the control group. Biomechanical testing showed the tensile strength was also significantly higher in the LD group using HCF than in other groups. The HCF system can provide a good option for the delivery of BMP-2 on posterolateral lumbar spine fusion.     

Neonatal Jaundice: Early Identification of Biliary Atresia

Biliary atresia is the number one indication for liver transplantation in children. The pathophysiology involves congenital or acquired damage to the bile ducts, which causes inadequate drainage and resultant liver failure. The diagnosis of biliary atresia is frequently missed due to the lack of standardized testing and few distinctive clinical manifestations. Newborns with biliary atresia usually appear healthy at birth and subsequently develop jaundice, acholic stools, and later ascites. Early intervention with the Kasai procedure is imperative to stop liver fibrosis and prevent premature death. Most children eventually require a liver transplant despite a successful Kasai procedure.     

Oxidative Stress Markers in Intestinal Mucosa of Tunisian Inflammatory Bowel Disease Patients

Background/Aims:

Inflammatory bowel diseases (IBDs), Crohn''s disease (CrD) and ulcerative colitis (UC), are chronic gastrointestinal inflammatory disorders. The precise etiology of IBD remains unclear, and it is thought that interactions among various factors, including, genetic factors, the host immune system and environmental factors, cause disruption of intestinal homeostasis, leading to dysregulated inflammatory responses of the gut. As inflammation is intimately related to formation of reactive intermediates, including, reactive oxygen species, oxidative stress has been proposed as a mechanism underlying the pathophysiology of IBD. The purpose of this study is to examine the lipid peroxidation, protein oxidation and anti-oxidative profile in Tunisian IBD.

Materials and Methods:

Malondialdehyde (MDA), conjugated dienes (CD), protein thiol levels, as well as the catalase (CAT) activity were evaluated in intestinal biopsies of 17 patients affected by IBD (12 CrD and 5 UC) and 12 healthy control individuals.

Results:

Oxidative stress was confirmed in these two types of disease biopsies as compared to controls. MDA and CD levels were significantly increased in both UC and CrD patients’ biopsies as compared to controls’ biopsies (P < 0.001). CAT activity was similar in UC and CrD biopsies’ and was not significantly increased in IBD patients’ biopsies compared with controls’ biopsies (P > 0.05). Anon-significant decrease in thiol (SH) level was observed in both UC and CrD patients’ biopsies compared with controls’ biopsies (P > 0.05).

Conclusion:

Increased levels of MDA and CD in IBD patients’ biopsies underline the implication of oxidative stress in the physiopathology of IBD.     

Pneumococcal conjugated vaccine: PHiD-CV

At the beginning of a new century, we have gained significant achievements against pneumococcal infections by using conjugated pneumococcal vaccines. In January 2009, the EMEA issued a positive opinion about, and recommended the approval of, GlaxoSmithKline’s pediatric pneumococcal candidate vaccine, which is indicated for active immunization against invasive pneumococcal disease (IPD) and acute otitis media caused by Streptococcus pneumoniae in infants and children from 6 weeks up to 2 years of age. The approved 10-valent pneumococcal vaccine (PHiD-CV) contains all serotypes in 7-valent pneumococcal conjugate vaccine (PCV-7) plus serotypes 1, 5 and 7F. Protein D from nontypeable Haemophilus influenzae is the carrier protein for eight serotypes, while tetanus and diphtheria toxins are in the carrier proteins for the remaining two serotypes. It has also been proved that PHiD-CV is immunogenic, safe and well-tolerated in children. This vaccine can be coadministered with routinely used pediatric vaccines. Noninferiority criteria of PHiD-CV compared with PCV-7 were established in shared serotypes, except for serotypes 6B and 23F, and PHiD-CV is immunogenic for additional serotypes as assessed by the percentage of subjects with antibody concentrations. PHiD-CV is also immunogenic for ten serotypes as assessed by post-primary and post-booster dose opsonophagocytic activity responses. Vaccine efficacy against IPD and other conditions should be monitored for shared serotypes and also additional serotypes during the postmarketing period. Optimal scheduling, safety and immunogenicity data in children with different risk factors for IPD, or whether it will provide herd immunity, are the questions waiting for answers in the postmarketing period. Further studies are needed to assess the potential advantages of protein D as a carrier and the potential efficacy of this new vaccine against H. influenzae. The potential public health efficacy of PHiD-CV in low-income countries, where IPD and pneumonia are a major public health problem, is a major concern.     

Polyunsaturated fatty acid saturation by gut lactic acid bacteria affecting host lipid composition

In the representative gut bacterium Lactobacillus plantarum, we identified genes encoding the enzymes involved in a saturation metabolism of polyunsaturated fatty acids and revealed in detail the metabolic pathway that generates hydroxy fatty acids, oxo fatty acids, conjugated fatty acids, and partially saturated trans-fatty acids as intermediates. Furthermore, we observed these intermediates, especially hydroxy fatty acids, in host organs. Levels of hydroxy fatty acids were much higher in specific pathogen-free mice than in germ-free mice, indicating that these fatty acids are generated through polyunsaturated fatty acids metabolism of gastrointestinal microorganisms. These findings suggested that lipid metabolism by gastrointestinal microbes affects the health of the host by modifying fatty acid composition.Dietary fats are metabolized not only by humans but also by microbes in our gastrointestinal tracts. Microorganisms in the gastrointestinal tract interact with their host in many ways and contribute significantly to the maintenance of host health (1). Lipid metabolism by gastrointestinal microbes generates multiple fatty acid species, such as conjugated fatty acids and trans-fatty acids, that can affect host lipid metabolism (2). However, lipid metabolism by gastrointestinal microbes has not been explored in detail. Saturation metabolism of polyunsaturated fatty acids, a representative mode of lipid metabolism by gastrointestinal microbes, is a detoxifying metabolism of anaerobic bacteria, such as lactic acid bacteria, that reside in colon and intestine. This process transforms growth-inhibiting free polyunsaturated fatty acids into less toxic free saturated fatty acids (3). This saturation metabolism generates characteristic fatty acids (e.g., conjugated fatty acids and trans-fatty acids, which are well known to present in ruminant-derived foods and exert various physiological activities).“Conjugated fatty acid” is a collective term for positional and geometric isomers of fatty acids with conjugated double bonds. In particular, conjugated linoleic acids (CLAs), such as cis-9,trans-11-CLA and trans-10,cis-12-CLA, reduce carcinogenesis (4), atherosclerosis (5), and body fat (6). With regard to lipid metabolism, CLA is a potent peroxisome proliferator-activated receptor (PPAR)α agonist (7), and treatment with CLA increases the catabolism of lipids in the liver of rodents (8). Based on these findings, CLA is now commercialized as a functional food for control of body weight, especially in the United States and European countries.On the other hand, consumption of trans-fatty acids increases the risk of coronary heart disease by increasing LDL and reducing HDL cholesterol levels (9). Consequently, trans-fatty acids are considered to be harmful for health, and nutritional authorities have recommended that consumption of trans-fatty acids be reduced to trace amounts (10). Therefore, it is important to control fatty acid saturation processes that generate these fatty acids (11); however, the precise metabolic pathway and enzymes involved have not been clearly identified.Our analyses on conjugated fatty acid synthesis in representative gut bacteria, the lactic acid bacteria (12–15), demonstrated that Lactobacillus plantarum AKU 1009a (AKU Culture Collection, Faculty of Agriculture, Kyoto University) can transform the cis-9,cis-12 diene structure of C18 fatty acids such as linoleic acid, α-linolenic acid, and γ-linolenic acid into the conjugated diene structures cis-9,trans-11 and trans-9,trans-11 (16–21). In addition, this strain can saturate these conjugated dienes into the trans-10 monoene. Our subsequent metabolic analysis indicated that 10-hydroxy-12-octadecenoic acid is an intermediate of CLA synthesis, and further investigations of hydroxy fatty acid metabolism by lactic acid bacteria revealed that CLA is produced from hydroxy fatty acids such as ricinoleic acid in castor oil (22–25). In cell-free extracts from this strain, we identified the enzymes involved in CLA synthesis (26). Three enzymes, CLA-HY, CLA-DH, and CLA-DC, are necessary for synthesis of conjugated fatty acids such as CLA. Only the combined action of these three enzymes can generate CLA from linoleic acid, with 10-hydroxy-cis-12-octadecenoic acid arising as an intermediate (Fig. 1B, 3). The reactions catalyzed by each enzyme, however, were not revealed in those studies. Through genomic analysis in L. plantarum WCFS1, we found that cla-dh (GenBank accession no. {"type":"entrez-nucleotide","attrs":{"text":"NC_004567","term_id":"380031102","term_text":"NC_004567"}}NC_004567; region: 59613-60473) and cla-dc (GenBank accession no. {"type":"entrez-nucleotide","attrs":{"text":"NC_004567","term_id":"380031102","term_text":"NC_004567"}}NC_004567; region: 60505-61350) are located in a cluster with another gene, cla-er (GenBank accession no. {"type":"entrez-nucleotide","attrs":{"text":"NC_004567","term_id":"380031102","term_text":"NC_004567"}}NC_004567; region: 61378-62031) (Fig. 1A). In light of this, we tried to identify the function of the gene product (CLA-ER) together with those of CLA-HY, CLA-DH, and CLA-DC.Open in a separate windowFig. 1.Gene clusters for polyunsaturated fatty acid metabolism and GC chromatograms. (A) Gene clusters for fatty acid metabolic enzymes in L. plantarum. (B) GC chromatograms of substrate (1); reaction with CLA-HY (2); reaction with CLA-HY, CLA-DH, and CLA-DC together with FAD and NADH (3); and reaction with CLA-HY, CLA-DH, CLA-DC, and CLA-ER together with FAD and NADH (4). I.S., internal standard.     

New Books Received

Almost every case of eclampsia is preventable. Prevention depends on prenatal care. The earliest possible detection of preeclampsia and of a rise in blood pressure is essential. Edema is the first warning sign; suggested treatment includes rest, minimum salt diet, and acetazolamide. Notification of eclampsia would be an effective weapon in reducing the incidence of the disease.     

Imaging and retention measurements of selenium 75 homocholic acid conjugated with taurine,and the carbon 14 glycochol breath test to document ileal dysfunction due to late radiation damage

In order to assess ileal dysfunction in patients with complaints after pelvic radiation therapy, retention measurements and scintigraphic imaging with selenium 75 homocholic acid conjugated with taurine (⁷⁵Se-HCAT), combined with the carbon 14 glycochol breath test, were evaluated in 39 patients. In 22 patients without ileal resection the results of the⁷⁵Se-HCAT test and the breath test differentiated between a normal functioning ileum (both tests negative) and ileal dysfunction as a cause of complaints (one or both tests positive). Among the patients with ileal dysfunction, the combination of both tests permitted those with bacterial overgrowth (breath test positive,⁷⁵Se-HCAT negative) to be separated from patients with evidence of bile acid malabsorption (⁷⁵Se-HCAT positive, breath test positive or negative). In 17 patients with small-bowel resection, the⁷⁵Se-HCAT test helped to estimate the severity of bile acid malabsorption with implications for therapy. In this group the breath test was false-negative in 7 cases with abnormal⁷⁵Se-HCAT. Additional systematically performed scintigraphic imaging improved the accuracy of the⁷⁵Se-HCAT test, revealing cases with prolonged colonic accumulation of the radiopharmaceutical, causing spurious retention values. In conclusion, assessment of ileal dysfunction by nuclear medicine techniques in post-irradiation conditions provides information about the aetiology and therefore the possibility of adjustment in the clinical management. Offprint requests to: R.A. Valdes Olmos