Challenges and opportunities for photochemists on the verge of solar energy conversion.

Has photochemistry missed the boat on solar energy conversion? Certainly not, but it is time to reach out and make a difference if we do not want to have to choose between feeding our families or our thirst for fuel. Compared to other initiatives, such as biofuels or nuclear fusion, direct conversion of solar energy into electricity or fuels is lagging behind in terms of funding, and this is slowing progress on overcoming critical bottlenecks. This perspective outlines some of the key fundamental issues in solar energy conversion based on organic photovoltaic devices or artificial photosynthesis where being a photochemist can make a difference.     

Collagen-specific T-cell repertoire in blood and synovial fluid varies with disease activity in early rheumatoid arthritis

Introduction  

Type II collagen is a DR4/DR1 restricted target of self-reactive T cells that sustain rheumatoid arthritis. The aim of the present study was to analyze the T-cell receptor repertoire at the onset of and at different phases in rheumatoid arthritis.     

Type IV Secretion-Dependent Activation of Host MAP Kinases Induces an Increased Proinflammatory Cytokine Response to Legionella pneumophila

The immune system must discriminate between pathogenic and nonpathogenic microbes in order to initiate an appropriate response. Toll-like receptors (TLRs) detect microbial components common to both pathogenic and nonpathogenic bacteria, whereas Nod-like receptors (NLRs) sense microbial components introduced into the host cytosol by the specialized secretion systems or pore-forming toxins of bacterial pathogens. The host signaling pathways that respond to bacterial secretion systems remain poorly understood. Infection with the pathogen Legionella pneumophila, which utilizes a type IV secretion system (T4SS), induced an increased proinflammatory cytokine response compared to avirulent bacteria in which the T4SS was inactivated. This enhanced response involved NF-κB activation by TLR signaling as well as Nod1 and Nod2 detection of type IV secretion. Furthermore, a TLR- and RIP2-independent pathway leading to p38 and SAPK/JNK MAPK activation was found to play an equally important role in the host response to virulent L. pneumophila. Activation of this MAPK pathway was T4SS-dependent and coordinated with TLR signaling to mount a robust proinflammatory cytokine response to virulent L. pneumophila. These findings define a previously uncharacterized host response to bacterial type IV secretion that activates MAPK signaling and demonstrate that coincident detection of multiple bacterial components enables immune discrimination between virulent and avirulent bacteria.     

Bisphosphonated fluoroquinolone esters as osteotropic prodrugs for the prevention of osteomyelitis

Osteomyelitis is a difficult to treat bacterial infection of the bone. Delivering antibacterial agents to the bone may overcome the difficulties in treating this illness by effectively concentrating the antibiotic at the site of infection and by limiting the toxicity that may result from systemic exposure to the large doses conventionally used. Using bisphosphonates as osteophilic functional groups, different forms of fluoroquinolone esters were synthesized and evaluated for their ability to bind bone and to release the parent antibacterial agent. Bisphosphonated glycolamide fluoroquinolone esters were found to present a profile consistent with effective and rapid bone binding and efficient release of the active drug moiety. They were assessed for their ability to prevent bone infection in vivo and were found to be effective when the free fluoroquinolones were not.     

Characterization of reproduction-specific genes in a marine bivalve mollusc: influence of maturation stage and sex on mRNA expression

Numerous studies have investigated the reproduction mechanisms in mollusc species at a biochemical and physiological level; few have described these mechanisms at a molecular level, despite great commercial interest in several mollusc species. We investigated genes involved in gonad maturation of the marine scallop Argopecten purpuratus. A cDNA library was made from gonad tissue. After sequence analysis, 418 unique genes were characterized, of these, about 80% were of unknown function. Among the identified sequences, we analyzed the mRNA expression by real-time PCR of 7 genes involved in reproduction mechanisms, either directly: testis-specific serine/threonine-protein kinase (TSSK), vitellogenin (Vg), and spermatogenesis and centriole associated 1 (SCA) or indirectly: calcineurin A (CNA), centrin, RNA-specific adenosine deaminase (ADAR), and cytidine deaminase (CDA). The real-time PCR analyses were conducted on different tissues of mature and immature scallops (testis, ovary, immature gonad, gill, digestive gland and mantle). The genes studied, presented (1) a strong tissue-dependent expression pattern (higher expression in gonad tissues than in all other tissues) and (2) a sex- and maturation-specific expression pattern (except centrin). This is the first time that the expression of specific genes involved in reproduction mechanisms in a marine mollusc has been described at the molecular level.     

Ulminium diluviale Unger : historique de la découverte et nouvelle étude

A fossil tree was discovered during the 16th century at Jáchymov (Bohemia). The wood was first named by Unger, in 1842, Ulminium diluviale. But it belongs to the Lauraceae family and Felix, in 1883, named it Laurinoxylon diluviale. The authors give the history and the geological setting of the area and describe the anatomy of the wood. The diagnosis of the genus Laurinoxylon Felix, 1883. is emended as follows: heteroxylous fossil wood with average sized solitary vessels or in radial groups; perforation plates simple and sometimes scalariform; intervascular pits alternate and moderately large; thyloses present. Paratracheal parenchyma. Uni to five seriate rays, slightly heterocellular and less than 1 mm high; ray-vessel pits large often stretched. Libriform or with radial pits fibres. Oil cells or mucilage (idioblasts) present. The diagnosis of the species Laurinoxylon diluviale (Unger) Felix, 1883. is also emended. Heteroxylous fossil wood with distinct growth rings; late wood poorly developed with vessels of diameter distinctly smaller as compared to the early wood and with smaller diameter fibres. Diffuse to semiporous vessels, solitary or in radial groups of two to seven , nine to 16 pores/mm²; tangential diameter 100 to 154 μm in early wood and 44 to 72 μm in late wood; vessel length 300 to 550 μm; perforation plates simple and scalariforme (6–12 bars); intervascular pits alternate, rounded (diameter 7–10 μm) or elliptic (long axes × short axes: 10–15 μm × 7–10 μm); thylosis present. Paratracheal parenchyma in more or less complete rows (1–2 cells wide) around the vessels. Heterocellular rays (1–(3) rows of upright cells), of one to five, more frequently three to four cells wide (80%); two to 36 cells high (60 to 820 μm); six to seven rays per tangential millimetre; vessels-rays pits sometimes large, stretched horizontally to vertically. Fibres of 15 to 25 μm in diameter; cell walls of 2–3 μm thick; pits not seen. Oil cells (idioblasts) at the ray margins; 27–60 μm in tangential diameter; 50–80 μm in radial diameter; 72–140 μm high; density of zero to 18 per transversal square millimetres depending on the observed area.     

Neuronal selectivity and local map structure in visual cortex

The organization of primary visual cortex (V1) into functional maps makes individual cells operate in a variety of contexts. For instance, some neurons lie in regions of fairly homogeneous orientation preference (iso-orientation domains), while others lie in regions with a variety of preferences (e.g., pinwheel centers). We asked whether this diversity in local map structure correlates with the degree of selectivity of spike responses. We used a combination of imaging and electrophysiology to reveal that neurons in regions of homogeneous orientation preference have much sharper tuning. Moreover, in both monkeys and cats, a common principle links the structure of the orientation map, on the spatial scale of dendritic integration, to the degree of selectivity of individual cells. We conclude that neural computation is not invariant across the cortical surface. This finding must factor into future theories of receptive field wiring and map development.     

Sympathovagal Balance,Nighttime Blood Pressure,and QT Intervals in Normotensive Obese Women

Objective : We describe associations among the heart‐rate‐corrected QT (QTc) interval, QTc dispersion (QTc‐d), circadian BP variation, and autonomic function in obese normotensive women and the effect of sustained weight loss. Research Methods and Procedures : In 71 obese (BMI = 37.14 ± 2.6 kg/m²) women, 25 to 44 years of age, circadian BP variations (24‐hour ambulatory BP monitoring), autonomic function (power spectral analysis of RR interval oscillations), and cardiac repolarization times (QTc‐d and QTc interval) were recorded at baseline and after 1 year of a multidisciplinary program of weight reduction. Results : Compared with nonobese age‐matched women (n = 28, BMI = 23 ± 2.0 kg/m²), obese women had higher values of QTc‐d (p < 0.05) and QTc (p < 0.05), an altered sympathovagal balance (ratio of low‐frequency/high‐frequency power, p < 0.01), and a blunted nocturnal drop in BP (p < 0.01). In obese women, QTc‐d and the QTc interval correlated with diastolic nighttime BP (p < 0.01) and sympathovagal balance (p < 0.01). Waist‐to‐hip ratio, free fatty acids, and plasma insulin levels correlated with QT intervals and reduced nocturnal drops in both systolic and diastolic BP and sympathovagal balance (p < 0.01). After 1 year, obese women lost at least 10% of their original weight, which was associated with decrements of QTc‐d (p < 0.02), the QTc interval (p < 0.05), nighttime BP (p < 0.01), and sympathovagal balance (p < 0.02). Discussion : Sustained weight loss is a safe method to ameliorate diastolic nighttime BP drop and sympathetic overactivity, which may reduce the cardiovascular risk in obese women.     

Decreased activity of cathepsins L+B and decreased invasive ability of PC3 prostate cancer cells

Cancer metastasis involves multiple factors, one of which is the production and secretion of matrix degrading proteases by the cancer cells. Many metastasizing cancer cells secrete the lysosomal proteases, cathepsins L and B, which implicates them in the metastatic process. Cathepsins L and B are regulated by endogenous cysteine proteinase inhibitors (CPI) known as cystatins. An imbalance between cathepsin L and/or B and cystatin expression/activity may be a characteristic of the metastatic phenotype. To determine whether cystatins can attenuate the invasive ability of PC3 prostate cancer cells, cells were transfected with a cDNA coding for chicken cystatin. Expression of chicken cystatin mRNA was determined by PCR analysis. Total cysteine proteinase inhibitory activity, cathepsins L+B activity, and invasion through a Matrigel® matrix were assessed. Stably transfected cells expressed the chicken cystatin mRNA and exhibited a significant decrease in secreted cathepsin L+B activity and a small increase in secreted cysteine proteinase inhibitor activity. The ability of cystatin transfected cells to invade the reconstituted basement membrane, Matrigel®, was attenuated compared to nontransfected cells or cells transfected with vector alone. We have demonstrated that the cysteine proteinases cathepsins L and B participate in the invasive ability of the PC3 prostate cancer cell line, and we discuss here the potential of using cysteine proteinase inhibitors such as the cystatins as anti-metastatic agents.